Methods and devices for surgical access

ABSTRACT

Devices, systems and surgical methods for achieving surgical access to a site within the body, particularly the spine. The system includes a modular retractor with a body and hood that are independently operable at their proximal ends to manipulate soft tissue at their distal ends, and may be adjustably and releasably coupled to form an open channel to a target tissue. On insertion, the hood is at least partially compressed against the retractor body. When coupled, the retractors are displaced from one another and constrained to one or more of at least three degrees of freedom, movable pivotally around a proximal end pivot axis that is perpendicular to the channel to adjust displacement of the retractors at their distal ends, displaceable vertically to adjust the distance between the retractors at their proximal ends, and slidable horizontally along the channel axis.

RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) to U.S.Provisional Application Ser. No. 62/021,202 filed Jul. 6, 2014, and No.62/080,609, 62/080,573, 62/080,578, 62/080,590, 62/080,557, all filedNov. 17, 2014, and No. 62/156,184, filed May 1, 2015, the entireties ofwhich are incorporated herein by reference.

BACKGROUND

1. Field

The present application describes various exemplary devices, systems andsurgical techniques for achieving access to a site within the body,particularly the spine. More particularly, the present applicationdescribes a system and device components for providing a minimallyinvasive retractor system for directly viewing and accessing a surgicalsite in the body, particularly the spine. In some exemplary embodiments,the system and device components are useful for accessing the spine forone or more purposes of manipulation, removal, replacement andreinforcement of intervertebral discs, particularly in the lumbar spine.According to such embodiments, the present invention overcomesshortcomings in the art.

2. Description of the Related Art

A common surgical approach for addressing spinal injuries andpathologies involves placement in the spine of one or more mechanicaldevices to enable clinical interventions for correcting the spine thatinclude intervertebral stabilization, distraction, decompression, jointfusion and combinations of these. There are a variety of such mechanicaldevices. For example, implants referred to as interbody devices areinserted between two adjacent vertebrae within the space that isnaturally occupied by the disc. Other devices, such as screws, plates,rods, and tethers are also used in various combinations, sometimestogether with interbody devices, to achieve desired correction to thespine. Specialized instrumentation is required for implantation of eachof these devices, and a wide range of surgical techniques and modes ofaccess to the spine have been developed, presenting a large array ofoptions and complexity for neurosurgeons and orthopedists who specializein the spine.

Broadly, there are at least three general modes of access to the spinefor achieving delivery of spinal correction devices. These general modesinclude anterior (through the abdominal cavity), posterior (includingtransforaminal), and lateral (including extreme lateral). For example,in the context of lumbar surgery, the lexicon includes the followingterms that describe these various modes of access for achieving fusionbetween lumbar vertebrae: anterior mode of access is known as “ALIF”(Anterior Lumbar Interbody Fusion); posterior mode of access is known as“PLIF” (Posterior Lumbar Interbody Fusion); an alternate, minimallyinvasive posterior mode of access is known as “TLIF” (TransforaminalLumbar Interbody Fusion); and lateral mode of access is know as “DLIF”(Direct Lumbar Interbody Fusion), including a minimally invasive lateralmode known as “XLIF” (eXtreme lateral Lumbar Interbody Fusion).Selection of the mode of access for a particular patient is dictated bya number of factors, including the extent of correction needed, thelocation within the spine requiring correction, and the preference andskill of the surgeon.

As with most other areas of surgery, is it preferable when operating onthe spine to employ the least invasive surgical approach possible forachieving correction to minimize trauma and associated pain and bloodloss experienced by the patient, to improve recovery time and outcomes,and to reduce operating room time and costs. Thus, while good resultshave historically been achieved through full-open access to the spine(typically through one of anterior and posterior routes), there issignificant attention to developing minimally invasive surgicalapproaches. Each of the various open and minimally invasive techniquesinvolve specialized instrumentation for achieving surgical access, andparticularly for the minimally invasive approaches, specialized deviceshave been developed that are adapted for delivery according to theselected technique and the associated instrumentation.

In accordance with the various methods of spinal access, there areseveral commonly shared requirements and steps. In all cases, it isnecessary for the surgeon to determine the proper size of the disc space(or spaces) to be accessed so as to select appropriately sizedimplant(s); this is typically achieved with preoperative imaging, inparticular, MRI and CAT scans. And a fluoroscopy machine (C-arm) is onhand to provide real-time x-ray images, particularly in those procedureswhere the spine cannot be directly visualized due to impedance of softtissue or small surgical field. In some instances, neuro-monitoringequipment is used to ensure that the instrumentation and implants arenot causing damage to spinal nerves. This equipment typically measuresspinal nerves indirectly by monitoring changes in leg muscle reflexesover time.

In all modes of approach, one or more special retractors and tubes aretypically used to dissect and displace tissue and expose the vertebrae,and other instruments are used to release the annulus and open the discspace, remove disc material, and prepare the space to receive animplant. Thereafter, one or more interbody implants is inserted in theprepared space, typically together with one of a variety of bone graftand osteogenic materials. In some examples, the implants are secured toone or both vertebral end plates using screws. During the procedures oneor multiple levels of fusion may be completed. Beyond these commonsteps, there is a good degree of variation in technique andinstrumentation for each of the modes of spinal access.

Anterior Access

Anterior Lumbar Interbody Fusion involves access to the spine from thefront (anterior) of the patient's body, usually through an incision inthe lower abdominal area or on the side. ALIF may be executed as afull-open procedure or as a minimally invasive procedure, for example,using laparoscopes, and involves cutting through, and later repairing,the muscles in the lower abdomen, and retracting (temporarily moving ordisplacing) muscles and blood vessels to gain access to the spine. ALIFadvantageously allows for direct access to the disc space at allvertebral levels without need to resect spinal bone and without traumato posterior muscles and nerves. Delivery of large sized implants ispossible via ALIF. Disadvantageously, for all ALIF procedures, thepatient must be in a supine position (on her/his back). Because it doesnot allow for posterior access to install pedicle screws, rods, tethersand other implants that stabilize the spine, the patient must berepositioned from supine to prone after the ALIF procedure is completedin order to gain posterior access to the spine. Repositioning typicallyextends the time in the operating room and can introduce additionalrisk. Further, ALIF access typically requires the involvement of othersurgeons, such as general surgeons, adding time and cost to theprocedure.

Posterior Access

Posterior Lumbar Interbody Fusion allows the vertebrae to be reachedthrough an incision in the patient's back (posterior). PLIF may beexecuted as a full-open procedure or as a minimally invasive procedure.One of the perceived key advantages to this approach is that the spineis accessed while the patient is in a prone position on the operatingtable, thus avoiding the need for the patient to be repositioned on thetable after an ALIF procedure, and allowing interbody placement to beachieved in parallel with pedicle screw and rod placement (i.e.,implantation of the interbody device at the same time as other fixationdevices). PLIF typically involves a 3-6 inch incision in the patient'sback and retraction of the spinal muscles and nerves to allow access tothe target intravertebral space, typically followed by removal of aportion of the vertebra called the lamina (laminectomy) and as needed,some portion of the facet joints. Thereafter, the affected disc materialis removed to accommodate implantation of the interbody device and bonegraft material. There are advantages to this surgical approach,including avoidance of the need for patient repositioning, and possiblyimproved rates of fusion due to the ability to achieve greatercompression. Some of the disadvantages include risk of retropulse of theimplant into the canal which can cause neural compression, andincomplete clearance of the disc space due to access limitations posedby posterior bone.

Transforaminal Lumbar Interbody Fusion is a refinement of the PLIFprocedure and has recently gained popularity as a minimally invasivesurgical technique for conditions affecting the lumbar spine. The TLIFtechnique involves approaching the spine in a similar manner as withPLIF but the spinal target site is displaced laterally, away from theposterior centerline of the spine and toward the side of the spinalcanal. As compared with PLIF, this approach enables a relatively reducedamount of surgical muscle dissection and nerve manipulation to accessthe disc space. And as compared with ALIF, this approach does notrequire the presence of a general surgeon, or the risks involved inaccess through the peritoneal cavity, or the need for rotation of thepatient. A key disadvantage to this mode of access is the requirementfor blunt dissection through the psoas muscle and the attendant problemof compression or dissection damage to nerve tissue that runs throughthe psoas muscle. This is particularly a problem since the field of viewavailable in the TLIF technique is very limited making accurateidentification of the nerve tissue a challenge.

Lateral Access

Direct Lumbar Interbody Fusion, and the minimally invasive counterpart,Extreme Lateral Lumbar Interbody Fusion, avoids an incision to theabdomen and avoids cutting and disrupting the muscles of the back.According to this mode of approach, the disk space is accessed from avery small incision on the patient's side (flank). The patient must bein a lateral recumbent or recovery position (on her/his side). Ascompared with PLIF, this approach reduces the amount of surgical muscledissection and is intended to minimize the nerve manipulation requiredto access the intervertebral space. And as compared with ALIF, thisapproach does not require the presence of a general surgeon, or therisks involved in access through the peritoneal cavity. But DLIF/XLIFspecifically presents some of the same challenges as TLIF in terms oftrauma to the posas muscle and possible neropraxia due to compressioncaused by the retraction instruments. And because the procedure does notallow posterior access, any procedures that require direct posterioraccess must be done serially rather than in parallel with the interbodyimplantation.

Posterior Lateral Access

Other less invasive lateral-type approaches have been developed orproposed using posterior entry and lateral access to the spine via acurvilinear path. Such systems rely on fixation of theinstrumentation/retractor either at its proximal end (i.e., proximate tothe surgeon, outside the patient's body) to structures having positionsthat are fixed relative to the spine (i.e., instruments that are fixedin space either through attachment directly to the spine or to otherfixed position structures), or at more than one location at the distalend (such as, for example, dorsal and ventral tangs that pierce into thedisc and/or inferior/posterior pins that engage with each of theadjacent vertebra. Experience with such systems that have actually beenmanufactured has shown that reliance on such fixation does noteffectively maintain the position of the curvilinear refractor at thespinal access site (ie, the instrument's portion that is distal relativeto the surgeon), resulting in significant slippage and/or displacementof the retractor from the spine during manipulations and implantplacement. Moreover, the visualization that is achieved usingsubstantially tubular curvilinear retractors is quite poor andimpractical for the useful conduct of surgical procedures within thedisc space.

While the overall curvilinear shape and the use of fixation means areintended to enable posterior lateral access, such systems areessentially rigid assemblies that don't allow the surgeon to manipulatesoft tissue in order to optimize positioning and securement, provideonly a limited effective view of the surgical field due to therelatively closed nature of the portal, and they don't ameliorate theconcussive forces involved in tissue removal and implant delivery. Theseand other disadvantages with existing posterior-lateral instruments andapproaches preclude the successful implementation a surgical approachthat is otherwise favorable for overcoming many of the limitations anddisadvantages of the TLIF, XLIF, and PLIF procedures and instruments.

There is a need for a surgical approach and associated instrumentationand devices that avoid the existing complications known in the art withthe various modes of spinal access. More specifically, there is a needfor advances with instrumentation and surgical technique to allow forthe more desirable prone patient positioning during spinal accesssurgery combined with the benefits of lateral access to the targetintervertebral space.

SUMMARY

In accordance with the disclosure, a direct visualization retractorsystem is disclosed which is adapted for surgical access, in particularsuitable for stable engagement with the spine, and which in variousembodiments is adjustable in a array of modes to accommodate a passageof surgical tools and implants. The system is particularly useful foruse on a patient in a prone position while achieving lateral access tothe spine, thus overcoming a host of disadvantages in the existing art.The direct visualization retractor system comprises a retractor bodycomponent and a retractor hood component, each of which operateindependently to achieve soft tissue retraction in a surgical field, andwhich fixedly engage together to establish a stable and open channelfrom the exterior of a patient's body to the target tissue, for examplethe spine.

In some embodiments, the present invention provides a method forperforming a procedure on the spine of a patient. The method alsoprovides for coupling the components in situ to form a directvisualization surgical retractor system for access to a surgical sitelocated at the spine of the patient. In accordance with the method,independent insertion and navigation of each of the retractor systemcomponents enables maximal dilation and retraction of soft tissue withenhanced tissue sparing. Each retractor system component isindependently placed adjacent to the target tissue, in the case ofinterbody fusion, the spine, using contoured features on the distal endsof the components. Nesting the hood component within the chute of theretractor component before coupling allows for maximal manipulation ofthe soft tissue prior to full tissue distraction. Upon engagement of theretractor system components, the various modes of adjustability enableoptimized placement of the hood and expansion of the access channel.Engagement of one or more tissue fixation members enables enhancedstabilization of the retractor system. The method further includesadvancing one or more surgical instruments and implants to the targettissue site. Instruments may include, for example, any one or more ofshims, osteotomes, tissue distractors, and inserters, and implants mayinclude, for example, any one or more of bone screws, plates, interbodydevices, artificial discs, and any other implants suitable for use inthe spine.

Embodiments of the present invention are not limited to use in aposterior-lateral approach for spinal surgery, and may also be used inmany other surgical approaches, including approaches to the spine, suchas anterior (ALIF), posterior (PLIF), transverse (TLIF), and extremelateral (XLIF). Embodiments of the present invention should also not belimited to the spine and may be used in other orientations and othersurgical sites within the body.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the general inventive concepts will becomeapparent from the following description made with reference to theaccompanying drawings, including drawings represented herein in theattached set of figures, of which the following is a brief description:

FIG. 1 is a schematic showing an assembled modular retractor inaccordance with the disclosure in relation to a spine as seen along theinferior to superior axis;

FIG. 2 includes in panel A a schematic showing a lateral view of aportion of a lumbar spine, and in panel B a schematic showing anincision guidance instrument in accordance with the disclosurepositioned relative to a portion of a lumbar spine in the context ofhuman anatomy;

FIG. 3 includes in panels A, B, C and D, respectively, schematicsshowing alternate oblique, top, oblique and side views of an assembledmodular retractor in accordance with the disclosure;

FIG. 4 is a schematic showing a side view of an assembled modularretractor in accordance with the disclosure wherein a series ofdifferent lengths of the retractor are shown nested to illustrateincremental modular component sizes;

FIG. 5 includes in panels A, B, C, D, E, F and G, respectively,alternate back, front, top, bottom, first and second side, and obliqueviews of an assembled modular retractor in a closed position inaccordance with the disclosure;

FIG. 6 includes in panels A, B, C, D, E, F and G, respectively,alternate back, front, top, bottom, first and second side, and obliqueviews of an assembled modular retractor in an open position inaccordance with the disclosure;

FIG. 7 includes in panels A, B, C, D, E, F and G, respectively,alternate exploded front, back, first and second side, top, bottom, andoblique views of a modular retractor in accordance with the disclosure;

FIG. 8 includes in panels A, B, C, D, E, F and G, respectively,alternate exploded front, back, first and second side, top, bottom, andoblique views of a fastening yoke of a modular retractor in accordancewith the disclosure;

FIG. 9 includes in panels A, B, C, D, E, F and G, respectively,alternate exploded back, front, top, bottom, first and second side, andoblique views of an alternate embodiment of an modular retractor inaccordance with the disclosure;

FIG. 10 includes in panels A, B, C, D, E, F and G, respectively,alternate back, front, top, bottom, first and second side, and obliqueviews of an alternate embodiment of a modular retractor in an openposition in accordance with the disclosure;

FIG. 11 includes in panels A, B, C, D, E, F and G, respectively,alternate exploded back, front, top, bottom, first and second side, andoblique views of an embodiment of an alternate embodiment of a fasteningyoke of a modular retractor in accordance with the disclosure;

FIG. 12 includes in panel A a schematic showing a side view of anembodiment of a modular retractor in an open position in accordance withthe disclosure indicating a radius of curvature and other features, andin panel B a radiographic image with an overlay of representative radiiof curvature of modular retractors and related instruments in accordancewith the disclosure relative to the disc of a human spine as shown in asuperior to inferior view;

FIG. 13 includes in panels A, B, C, D, E, F and G, respectively,alternate back, front, top, bottom, first and second side, and obliqueviews of an embodiment of a fixation tissue securement guide forengagement with a modular refractor in accordance with the disclosure;

FIG. 14 includes in panel A a schematic of a distal/front end of amodular retractor in a partially closed position in accordance with thedisclosure including a slidable retractor blade for optimizingpositioning; and in panel B a modular refractor of panel A depicted inthe context of a portion of a human spine and adjacent to the L4/L5 discinterface from an anterior perspective; and in panel C same modularretractor depicted in the context of a portion of a human spine andadjacent to the L4/L5 disc interface from an posterior perspective, andin panels D, E, F, G, H, I and J, respectively, alternate left and rightback, left and right front, left and right top, left and right bottom,left and right left side, left and right right side, and left and rightoblique views of an embodiment of a slidable refractor blade for amodular retractor in accordance with the disclosure;

FIG. 15 is a schematic showing an incision guidance instrument inaccordance with the disclosure positioned relative to a portion of humananatomy;

FIG. 16 includes in panels A, B, C, D, E, F and G, respectively,alternate back, front, top, bottom, first and second side, and obliqueviews of an incision guidance instrument in accordance with thedisclosure;

FIG. 17 shows in panel A a radiographic image from a human model showingan anterior to posterior (AP) view of a human spine over which ispositioned on the patient an incision guidance instrument, and in panelB a radiographic image from a human model showing a lateral view of ahuman spine over which is positioned on the patient an incision guidanceinstrument, the schematic showing the orientation of the arm of theguidance instrument relative to an intervertebral disc space and theoverlying skin surface for determining incision location;

FIG. 18 includes oblique views of each of the insertion instruments,including in panel A speculum shoehorn, in panel B a hand heldretractor, in panel C a ribbon blade, in panel D an awl, panel E abilateral retractor, in panel F a hood handle, in panel G a shim, and inpanel H a driver;

FIG. 19 includes in panels A, B, and C respectively front, back andoblique views of an embodiment of a first dilator, in panels D, E and F,respectively, front, back and oblique views of an embodiment of thesecond dilator, and in panels G, H and I, respectively, front, back andoblique views of an embodiment of an tang awl;

FIG. 20 includes in panel A a schematic showing the insertion paththrough human anatomy and orientation relative to the spine of insertioninstruments in accordance with the disclosure, and in panel B aphotograph showing the insertion instruments of panel A as inserted intoa human model;

FIG. 21 includes in panel A an alternate view of the schematic shown inFIG. 20A further depicting the insertion of an awl, and in panel Banother alternate view of the schematic shown in FIG. 20A furtherdepicting the insertion of a first elongate dilator, and in panel Canother alternate view of the schematic shown in FIG. 20A furtherdepicting the insertion of a first elongate dilator and a ribbon blade,and in panel D another alternate view of the schematic shown in FIG. 20Afurther depicting the insertion of a second elongate dilator adjacent tothe first elongate dilator and a ribbon blade;

FIG. 22 includes in panel A another alternate view of the schematicshown in FIG. 20A further depicting the insertion of an tang awladjacent to the second elongate dilator and a ribbon blade, and in panelB a photograph showing the insertion instruments of panel A as insertedinto a human model;

FIG. 23 includes in panel A another alternate view of the schematicshown in FIG. 20A further depicting the insertion of a modular retractorcomponent adjacent to the second elongate dilator and ribbon blade, andin panel B a photograph showing the insertion instruments of panel A asinserted into a human model;

FIG. 24 includes in panel A another alternate view of the schematicshown in FIG. 20A further depicting the insertion of a second modularretractor component adjacent to the first modular retractor componentusing a handle, and in panel B a photograph showing the insertioninstruments of panel A as inserted into a human model, and in panel C aschematic showing the instruments of panel B with a neuro-monitoringprobe inserted therein, and in panel D a schematic showing the assembledand positioned adjacent to the spine and affixed with a table arm;

FIG. 25 includes in panel A a schematic showing an embodiment of atissue cutting assembly inserted through a modular retractor andpositioned adjacent to a spine, and in panel B a close up of thedistal/front end of a blade of a cutting assembly depicting insertionthrough and into a disc;

FIG. 26 includes in panel A a close up of the distal/front end of apunch blade of a cutting assembly depicting insertion of the punch bladethrough and into a disc toward the contralateral disc annulus, and inpanel B a radiographic image from a human model showing an anterior toposterior (AP) view of a human spine showing insertion of the punchblade as depicted in panel A;

FIG. 27 includes in panel A a radiographic image from a human modelshowing an anterior to posterior (AP) view of a human spine showingpositioning of an paddle distractor within the disc space forpreparation thereof to receive an implant, and in panel B a schematicshowing an embodiment of an tissue preparation device and a disc implantfor attachment thereto, and in panel C a schematic showing an obliqueproximal/back end view of the tissue preparation device inserted throughthe modular retractor depicting transit of the implant along the path ofthe retractor and toward the disc space by actuation of the instrumentdriver;

FIG. 28 includes in panel A a view of the tissue preparation device andattached implant inserted through a modular retractor and positionedadjacent to a spine depicting insertion of the implant into the discspace, and in panel B a schematic showing an a close up side view of thedistal/front end of the modular retractor with the tissue preparationdevice inserted there through depicting positioning of the implantwithin the disc space, and in Panel C a radiographic image from a humanmodel showing an anterior to posterior (AP) view of a human spineshowing positioning the implant within the disc space as evidenced bythe tantalum marker on the distal end of the implant contralateral tothe position of the retractor;

FIG. 29 includes in panels A, B, C, D, E, F and G, respectively,alternate back, front, first and second side, bottom, top, and obliqueviews of a nested and partially exploded assembly of dilationinstruments for assembly of a modular retractor in accordance with thedisclosure;

FIG. 30 includes in panels A, B, C, D, E, F and G, respectively,alternate back, front, first and second side, top, bottom, and obliqueviews of a first embodiment of a cutting assembly having an impact driveplate in accordance with the disclosure;

FIG. 31 includes in panel A an exploded view of the embodiment of thecutting assembly shown in FIG. 30 showing the attachment of theremovable blade to the instrument, and in Panel B an exploded view of analternate embodiment of a cutting assembly having an rotational drive inaccordance with the disclosure showing the attachment of the removableblade to the instrument;

FIG. 32 includes in panels A, B, C, D, E, and F, respectively, oblique,top, oblique, oblique, side, and oblique views of a first embodiment ofa tissue preparation device having a rotational drive in accordance withthe disclosure;

FIG. 33 includes in panel A top views of a surgical table according tothe disclosure showing in successive frames a pivoting support inneutral and right pivot orientations and left pivot orientation with andwithout a prone subject, and in panel B top views as shown in panel Ashowing in successive frames the surgical table including conventionalpads with and without a prone subject and with the support platform ofthe pivoting support removed, and in panel C an end view of the pivotingsupport showing opposing right and left bolsters and table frame tracks;

FIG. 34 includes in panel A top views of a conventional surgical tableshowing in successive frames conventional table pads with and without aprone subject, and in panel B an end view showing opposing right andleft bolsters;

FIG. 35 includes in panel A top views of neutral, left and right pivotorientations of a pivoting support according to the disclosure, and inpanel B a bottom view of the support platform of a pivoting support, andin panel C a top view of the pivot track of a pivot platform, and inpanel D alternate views of a crank/lock mechanism for actuating andlocking the pivot position of a pivoting support;

FIG. 36 includes in panel A a schematic showing an inferior to superiordorsal view of a portion of a lumbar spine in a neutral positionfeaturing the relative position of the hip relative to the L4/L5 discspace, and in panel B a schematic showing an inferior to superior dorsalview of a portion of a lumbar spine in a left pivot positionillustrating the relative shift of the hip to enhance exposure of theL4/L5 disc space;

FIG. 37 is an oblique view of an alternate embodiment of an assembledmodular retractor in accordance with the disclosure;

FIG. 38 is an oblique view of an alternate embodiment of an assembledmodular retractor in accordance with the disclosure;

FIG. 39 is an oblique view of an alternate embodiment of an assembledmodular retractor in accordance with the disclosure;

FIG. 40 is an oblique view of an alternate embodiment of an assembledmodular retractor in accordance with the disclosure;

FIG. 41 is an oblique view of an alternate embodiment of an assembledmodular retractor in accordance with the disclosure;

FIG. 42 is an oblique view of an alternate embodiment of an assembledmodular retractor in accordance with the disclosure; and,

FIG. 43 is an oblique view of an alternate embodiment of an assembledmodular retractor in accordance with the disclosure.

This disclosure describes exemplary embodiments in accordance with thegeneral inventive concepts and is not intended to limit the scope of theinvention in any way. Indeed, the invention as described in thespecification is broader than and unlimited by the exemplary embodimentsset forth herein, and the terms used herein have their full ordinarymeaning.

DETAILED DESCRIPTION

The general inventive concepts will now be described with occasionalreference to the exemplary embodiments of the invention. The generalinventive concepts may be embodied in different forms and should not beconstrued as limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the general inventiveconcepts to those skilled in the art.

This disclosure describes exemplary embodiments in accordance with thegeneral inventive concepts and is not intended to limit the scope of theinvention in any way. Indeed, the invention as described in thespecification is broader than and unlimited by the exemplary embodimentsand examples set forth herein, and the terms used herein have their fullordinary meaning.

The general inventive concepts are described with occasional referenceto the exemplary embodiments of the invention. Unless otherwise defined,all technical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skill in the art encompassing thegeneral inventive concepts. The terminology set forth in this detaileddescription is for describing particular embodiments only and is notintended to be limiting of the general inventive concepts.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The term “proximal” as used in connection with any objectrefers to the portion of the object that is closest to the operator ofthe object (or some other stated reference point), and the term “distal”refers to the portion of the object that is farthest from the operatorof the object (or some other stated reference point). The term“operator” means and refers to any professional or paraprofessional whodelivers clinical care to a medical patient, particularly in connectionwith the delivery of care.

With respect to any references herein that may be made relative to ahuman patient, the terms “cephalad,” “cranial” and “superior” indicate adirection toward the head, and the terms “caudad” and “inferior”indicate a direction toward the feet. Likewise the terms “dorsal” and“posterior” indicate a direction toward the back, and the terms“ventral” and “anterior” indicate a direction toward the front. And theterm “lateral” indicates a direction toward a side of the patient, theterm “medial” indicates a direction toward the mid line of the patient,and away from the side, the term “ipsalateral” indicates a directiontoward a side that is proximal to the operator or the object beingreferenced, and the term “contralateral” indicates a direction toward aside that is distal to the operator or the object being referenced. Moregenerally, any and all terms providing spatial references to anatomicalfeatures shall have meaning that is customary in the art.

Unless otherwise indicated, all numbers expressing quantities,properties, and so forth as used in the specification, drawings andclaims are to be understood as being modified in all instances by theterm “about.” Accordingly, unless otherwise indicated, the numericalproperties set forth in the specification and claims are approximationsthat may vary depending on the suitable properties desired inembodiments of the present invention. Notwithstanding that the numericalranges and parameters setting forth the broad scope of the generalinventive concepts are approximations, the numerical values set forth inthe specific examples are reported as precisely as possible. Anynumerical values, however, inherently contain certain errors necessarilyresulting from error found in their respective measurements.

References to visualization using radiography as described in theexemplary techniques herein are merely representative of the options forthe operator to visualize the surgical field and the patient in one ofmany available modalities. It will be understood by one of ordinaryskill in the art that alternate devices and alternate modalities ofvisualization may be employed depending on the availability in theoperating room, the preferences of the operator and other factorsrelating to exposure limits. While confirmation of instrument placementin the course of the technique is appropriate, the frequency and timingrelative to the sequence of steps in the technique may be varied and thedescription herein is not intended to be limiting. Accordingly, more orfewer images, from more or fewer perspectives, may be collected.

One of ordinary skill will appreciate that references to positions inthe body are merely representative for a particular surgical approach,and according to the exemplary embodiments herein, are based on arepresentative spinal access refractor system having a radius ofcurvature as described, being suitable for any number of animalpatients, including humans and other species. Of course, the type ofsurgery, target tissue, and species of patient may be different than isdisclosed in the exemplary embodiments described herein, and in someembodiments, all or most components of the system may be rectilinear.

Further, all references herein are made in the context of therepresentative images shown in the drawings. Fewer or additional genericinstruments may be used according to the preference of the operator.Moreover, references herein to specific instruments are not intended tobe limiting in terms of the options for use of other instruments wheregeneric options are available, or according to the preference of theoperator.

Modular Retractor and Direct Visualization Channel

As described herein above, there is a need for devices and systems thatovercome the shortcomings in the art pertaining to minimally invasivesurgical access, particularly access for spinal surgery. In view of thisneed, the embodiments of devices, systems, and surgical methods providedherein address a variety of objects and advantages. The presentapplication describes various exemplary devices, systems and surgicalmethods for achieving surgical access to a site within the body,particularly the spine. More particularly, the present applicationdescribes a system and device components for providing a minimallyinvasive retractor system for directly viewing and accessing a surgicalsite in the body, particularly the spine. In some exemplary embodiments,the system and device components are useful for accessing the spine forone or more purposes of neural decompression, manipulation, removal, andreplacement and reinforcement of intervertebral discs, particularly inthe lumbar spine.

Referring now to the drawings, FIG. 1 is a schematic showing anassembled modular retractor in accordance with the disclosure inrelation to a spine as seen along the inferior to superior axis. Incertain embodiments, the retractor system is suitable for facilitatinginterbody fusion between adjacent vertebrae, and in particular, lumbarinterbody fusion. Referring to the representative embodiment of theretractor system shown in FIG. 1, the direct visualization retractorsystem enables creation of an open and essentially unobstructed channelfor visualizing and surgically accessing the spine. As more fullydescribed herein below and in the representative drawings, the refractorsystem includes, in various embodiments, features that enable stablepositioning relative to the spine, and tissue-sparing retraction ofnerves and muscle. Advantageously, in certain embodiments, a curvilinearshape of the direct visualization retractor system, as depicted in FIG.1, is particularly well suited for achieving lateral approach to thespine through a posterior access site.

The posterior-lateral procedure begins with placing a patient in a proneposition on a surgical table (eg., Jackson Table) with the axis of thelumbar spine generally parallel with the operating room floor.Posterior-lateral access and prone positioning of the patient offersmany advantages over the current alternative approaches to LIF,including, but not limited to: eliminating the need to reposition thepatient for posterior stabilization and minimizing risk to vital softtissues as compared with ALIF; minimizing nerve compression compared toa straight oblique approach; delivering an implant with better anatomicphysiology without requiring drastic repositioning; protecting anterioraspect and protecting the bowels from injury; preserving posterior bone;allowing use of a larger implant and avoidance of bone removal ascompared with TLIF; and presenting the patient in manner that is morefamiliar to the typical spine surgeon and more comfortable for thesurgical subject as compared with the XLIF and other direct lateral LIFprocedures.

Of course, it will be appreciated that other modes of access to thespine can also be achieved, particularly with alternate, non-curvilinearembodiments of the retractor system, as described herein below.Likewise, it will be appreciated that any one or more of a variety ofsurgical procedures can be performed through the direct visualizationretractor system, including but not limited to, removal of annulusmaterial, vertebral distraction, graft and/or interbody implantinsertion, and attachment of one or more plates and/or screws. Inaddition to enabling direct visualization for a lateral approach to thespine, other specific features and advantages of the retractor systemand the surgical technique are described further herein.

In accordance with the surgical techniques described herein, the systemprovides the option for placement of a retractor system for accessingthe spine. In some embodiments of the surgical techniques, an incisionguidance instrument is used for selecting a desirable incision site forinsertion of the retractor system to achieve placement at the desiredlocation relative to a target spinal intervertebral space. Referringagain to the drawings, FIG. 2 shows an exemplary embodiment of anincision guidance instrument in accordance with the disclosure, theinstrument positioned relative to a portion of a lumbar spine in thecontext of human anatomy. FIG. 2 Panel A is a schematic showing alateral view of a portion of a lumbar spine and panel B a schematicshowing key spinal landmarks that are relevant to the positioning of theincision guidance instrument and selection of the incision site.

Referring now to FIG. 3, the direct visualization retractor system isadapted for engagement at its distal end with the spine and comprisesrefractor body and hood components, each of which is discretely operableto achieve dilation and retraction of soft tissue, and which are adaptedfor inter-engagement in a variety of configurations to provide anadjustable and stable retractor system. FIG. 3 includes in panels A, B,C and D, respectively, schematics showing alternate oblique, top,oblique and side views of an assembled modular retractor in an openconfiguration, in accordance with the disclosure. And FIG. 4 is aschematic showing a side view of an assembled modular retractor inaccordance with the disclosure wherein a series of different lengths ofthe retractor hood and body are shown nested to illustrate exemplaryincremental modular component sizes. A representative modular retractordevice and its components are shown in various views in FIG. 5-FIG. 11,particulars of which will be described in detail herein below.

While various features and aspects of the modular retractor may varyaccording to the disclosure, in some embodiments of the instantinvention, the retractor components are particularly suited forposterior-lateral access to the spine, wherein one or more componentshas a generally curved profile, being curved along an elongate axis. Inyet other embodiments, the devices and systems are particularly suitedfor a surgical procedure that is achieved along a generally rectilinear(i.e., uncurving) path, such as via a direct anterior, posterior, orlateral approach wherein suitable embodiments of the device and systemcomponents are essentially rectilinear, or have a nominal curvature witha radius of curvature.

Referring now to FIG. 12, panel A is a schematic showing a side view ofan embodiment of a modular retractor in an open position in accordancewith the disclosure, the schematic indicating a radius of curvatureR175, and also indicating the arc of an alternate optional radius ofcurvature R150. Panel B is a radiographic image of a human spine asshown in a superior to inferior view (also included in the image is arepresentative embodiment of an incision guidance instrument) with anoverlay of six alternate representative radii of curvature. As shownrelative to the disc, which is shown from an inferior to superiorperspective, the path of the radius transects the disc approximately atits centerline and the radius is essentially coaxial with the centerlineradius of the channel formed by the modular retractor. The depictedrefractor includes a curvilinear retractor body, positioned ventrallyand an essentially rectilinear hood positioned dorsally.

It will be appreciated by one of skill that the radius of the retractorand other instruments, as described herein below, are influenced by theselected radius of curvature for achieving lateral access to the discspace. Generally, the greater the radius, the flatter the channel andinstruments, dictating a more ventral incision site on the patient, andthe smaller the radius, the steeper the channel and instruments,dictating a more dorsal incision site on the patient. Thus, the pointsof access in the spine relative to the anterior to the center line tothe posterior edge of the disc space may vary to accommodate theselected radius of curvature or lack thereof and enable delivery of animplant along the retractor to align with the centerline of the discspace.

Without being limiting, the radius of curvature of instruments accordingto the disclosure may be within a range from about 0 cm to about 60 cm,and more particularly from about 5 cm to about 25 cm, and in someembodiments the radius may be selected from one of 15 cm, 17 cm, 17.5cm, 18 cm, 22 cm, 22.5 cm, and 25 cm. Of course other radii are possiblewithin the range from 0 cm to more than 60 cm, including 0, 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,and 60, and incremental fractions thereof including 0.1, 0.2, 0.3, 0.4,0.5, 0.6, 0.7, 0.8, 0.9 cm.

Referring again to the drawings, FIG. 3, the exemplary modular directvisualization retractor system includes elongate retractor body and hoodcomponents, each of which is operable independently for soft tissueretraction, and which fixedly couple to form the retractor system andestablish a stable and open channel from the exterior of a patient'sbody to the target tissue. The modular direct visualization retractorsystem has a cross section that is generally elliptical or polygonal inshape, as shown in representative FIG. 3A.

Each of the elongate retractor body and hood components has a proximalend that is adapted to extend outside of the patient, and a distal endthat is adapted for contact with the target tissue. The elongaterefractor body depicted in the drawings is generally chute or troughshaped, the chute extending along a longitudinal axis between theproximal and distal ends, with a refractor floor and two opposingsidewalls that define the chute, and an open top. In some embodiments,as shown in FIG. 38, FIG. 39 and FIG. 40, at the retractor body'sproximal end is a retractor body handle that is oriented relative to thechute at a downward angle, and most typically at an angle that isbetween 5 and 90 degrees. The exemplified handle shown in any one of thedrawings is, of course, non limiting, and the relative length and shapeof the handle may vary. Likewise, the angle of orientation may be 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58,59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76,77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94,95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109,110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123,124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137,138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151,152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165,166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, or 179degrees. Further, such handle may be removable, rotatable, pitched tothe left or the right relative to the body of the retractor, andcombinations of these.

Referring again to representative FIG. 3, the elongate hood is agenerally planar narrow elongate body that extends along a longitudinalaxis between the proximal and distal ends, and has a soft tissueelevator at its distal end, where in the depicted embodiment, the distalend is dipped to provide a recess between the more proximal portion ofthe planar body of the hood and an upwardly deflected tip. In someembodiments, as shown in FIG. 3E, at the hood's proximal end is adetachable hood guide that is used as a handle to guide and manipulatethe hood within the incision, the guide oriented relative to the body ofthe hood at an upward angle that is between 5 and 90 degrees. Alternateviews of a non-limiting embodiment of a handle are shown in FIG. 3F andFIG. 3G. The exemplified handle shown in any one of the drawings is, ofcourse, non limiting, and the relative length and shape of the handlemay vary. Likewise, the angle of orientation may be 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97,98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112,113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126,127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154,155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168,169, 170, 171, 172, 173, 174, 175, 176, 177, 178, or 179 degrees.Further, such handle may be removable, rotatable, pitched to the left orthe right relative to the body of the retractor, and combinations ofthese.

At their proximal ends, each of the retractor and the hood includes acoupling element for joining them together to form the modular directvisualization retractor system. The coupling elements include one or aplurality of fasteners, for example, pins, on one or the other of therefractor and hood, and one or a plurality of receivers, for exampleelongate slots, on the other of the retractor and the hood. Inoperation, the fasteners (e.g., pin(s)) slidably engage in the receivers(e.g., elongate slot receiver(s)) to couple the hood to the retractor toform the surgical access retractor system, and are adapted to enablerelative pivoting of the hood and refractor at their proximal ends, andrelative sliding of the hood and retractor along the common longitudinalaxis of the refractor system.

Referring again to the drawings, FIG. 8, for example, shows anembodiment of an coupling system engagable with exemplary couplingelements on the retractor body and hood, shown, for example, in FIG. 7.Referring again to FIG. 7, the depicted embodiment of the retractorincludes a pair of opposing proximally extending pins on the left andright sides at the proximal end of the retractor body, and a pair ofopposing proximally extending tabs on the proximal end of the hood, eachof which pairs of pins and tabs respectively engage with the yokecomponent coupling system shown in FIG. 8.

In various embodiments, the direct visualization retractor system hasexternal dimensions that are suited for insertion through an incision ina patient's skin and passage to an internal target tissue site, andinternal channel dimensions that are suited for the passage therethroughof instruments and implants for use on the target tissue. In variousembodiments, it may be desirable for each of the retractor body and hoodcomponents to have the same length, and in yet other embodiments, it maybe desirable for the hood to be longer or shorter than the retractorbody. In one example, the hood may be shorter than the retractor bodyfor certain spinal surgery applications, where the posterior bonystructures of the spine would interfere with the distal end of the hood.In yet other examples, one or more of the radius of the systemcomponents and the particular patient anatomy may necessitate selectionof a hood that is longer than the retractor body in order to ensure goodengagement at the proximal end and suitable contact with the targettissue at the distal and of the hood.

Referring again to FIG. 4, examples of varied length hood and refractorbody components are shown nested in a schematic that illustrates someoptions for relative hood and retractor body length. It will beappreciated by one of ordinary skill that the absolute dimensions of therefractor components may be varied to accommodate the dimensions of thebody parts and tissue being targeted, and that any specific dimensionsshown or described herein are not limiting.

The retractor and the hood are specifically adapted to be independentlyguided and inserted, in series, into an incision in the patient's skinto allow for manipulation and retraction of soft tissue, and can becoupled in situ to form the direct visualization retractor system. Inuse, the refractor is useful for supplementing tissue dilation anddistraction, and for establishing the channel through which the targettissue will be surgically accessed. Each of the retractor and hoodcomponents has a width dimension that is generally perpendicular to andruns substantially along the collinear longitudinal axes. In someembodiments, the width of the hood is less than the width of therefractor, such that the hood can be retractor support at leastpartially recessed within the chute of the retractor before coupling toform the retractor system.

In various embodiments, the distal end of one or both the retractor bodyand retractor hood is contoured and the contour describes a concave arcthat transects the retractor's longitudinal axis and has a radius ofcurvature from about 0.5 cm to 10 cm. In some embodiments, the contouris bounded by bosses. Referring again to the drawings, FIG. 7F, forexample, shows the distal end of the retractor body having a curve thatis bounded by bosses. These features enhance the engagement of theretractor with the spine and stabilize it during use. FIG. 7F likewiseshows a modest radius on the distal tip of the hood retractor. Inaddition, the hood retractor, as shown, has a tissue elevator at thedistal end that is recessed (curved or dipped) relative to an externalsurface of the hood, and has a width dimension that is less than a widthdimension of the proximal end of the hood. Thus, in various embodiments,a contour at a retractor distal end may have a radius in cm andincrements in between including 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 cm.

The modular direct visualization retractor system is adjustable in avariety of modes to allow an unobstructed view of and access to thesurgical site for manipulation of tissue and to accommodate passage ofsurgical instruments and implants. For example, in one mode ofadjustment, the distance between the distal ends of the retractor andhood can be adjusted by rotation at the coupling, whereby the distal andproximal ends of the retractor system can be adjusted to have variablysized distal openings while the distance between them at the proximalend remains essentially fixed. Referring again to the drawings, FIG. 5shows a representative embodiment wherein the assembled retractor systemis in a closed configuration, with the distal end of the hood restingwithin and in contact with the retractor body. FIG. 6 shows the samerepresentative embodiment wherein the assembled retractor is in an openconfiguration. In another mode of adjustment, the retractor and hood canbe slidably translated along the collinear longitudinal axes so that therelative positions of the distal and proximal ends of the retractor andhood can be varied. And in yet another mode of adjustment, the relativevertical distance between the hood and the retractor can be adjusted.

Examples of retractor devices having two modes of adjustment are shownFIG. 4, for example, and also in different embodiments shown in FIG. 37and FIG. 43, wherein the hood may be rotated pivotally to raise andlower its distal end and it may be displaced laterally along its axisthat is collinear with the retractor body.

Referring again to the drawings, FIG. 38 depicts a representativeexample of a retractor device wherein three modes of adjustability areenabled. Referring to the drawing, the hood can be raised or loweredfrom the retractor body by vertical adjustment of a lockable channelexpander comprising a primary yoke on the retractor body handle thatcomprises opposing clips for slidable engagement with the hood, andwherein the hood may be rotated pivotally to raise and lower its distalend by actuation of the tabbed yoke on the hood. In addition, as shownin representative FIG. 38, the hood and retractor body may be displacedlaterally along their collinear axes by translation of the hood withinthe G shaped clips at the top end of the yoke on the retractor bodyhandle. In yet other embodiments, the retractor device may be adjustableonly in one mode, for example, pivotal rotation at a proximal axis toadjust the distance between the distal ends of the hood and retractorbody.

In the various disclosed embodiments, the modes of adjustability of theretractor components enable customized adjustment of the retractorsystem to accommodate one or more of positioning relative to the targettissue site, manipulation of tissue to minimize tissue creep within thechannel, relief of compression of soft tissue, and adaptation of thechannel for passage of varying sized instruments and implants.

In some embodiments, at least one of the retractor and hood alsoincludes at least one tissue fixation member. A tissue fixation memberis useful for firmly securing one or more of the refractor, the hood andthe retractor system to tissue. A tissue fixation member includes aretractor system securement element that is securable to the surgicalaccess retractor system, and a tissue securement element that issecurable to the target tissue site. In various embodiments, the tissuesecurement element is selected from a screw, a pin, a wire, an awl, anda tang, and other implements that can be removably affixed to tissue,particularly bone.

In some representative embodiments, the retractor includes as a tissuefixation member an elongate tang that is oriented along the longitudinalaxis and is adjacent to the retractor floor and extends beyond thedistal end. Referring now to exemplary FIG. 6G and FIG. 7G, the tang isslidable within a receiving slot in the floor of the retractor body andextends therefrom for insertion into the target tissue. In use, the tangmay be assembled with the retractor body on its insertion adjacent tothe target tissue, or may be slid into place after the retractor body ispositioned on the tissue, the end of the tang being extended at apreferred distance from the retractor body distal end.

In other embodiments, the securement element is a screw, the devicefurther comprising a screw placement guide securable to either the hoodor the body, and a driver engageable with the guide. Referring again tothe drawings, FIG. 13 shows an exemplary embodiment of a tissue fixationmember comprising a retractor securement element in the form of a screwplacement guide comprising an elongated arm that is securable to areceiving channel on an extended sidewall of the depicted hood, theelongated arm comprising at a proximal end a tab that engages with thehood receiving channel, and at its distal end a locking ring forsecuring a driver for delivering the pin or screw to the tissue and forengaging a pin or screw (not shown) passed there though and affixed tothe target tissue. FIG. 7 shows the exemplary tissue fixation member inthe context of an exploded depiction of an embodiment of the retractordevice. Of course it will be appreciated by one of ordinary skill in theart that the exemplary tissue fixation member may be varied in itsattachment to one or the other of the retractor hood and refractor body,and may likewise have a different engagement with the pin or screw.

In some embodiments, the retractor device includes an adapter forenhancing contact with the target tissue. For example, a shim or otheradapter may be used to accommodate gaps between the distal end of theretractor body where anatomical structures such as bone spurs impedeoptimal contact of the end of the retractor with the tissue or theanatomy otherwise interferes such as the hip bones interference withaccess to the L4/L5 disc. Referring again to the drawings, FIG. 14includes in panel A a schematic of a distal/front end of a modularretractor in a partially closed position in accordance with thedisclosure including a slidable retractor blade for optimizingpositioning. FIG. 14 panel B shows a modular retractor of panel Adepicted in the context of a portion of a human spine and adjacent tothe L4/L5 disc interface from an anterior perspective, and panel C showsthe same modular retractor depicted in the context of a portion of ahuman spine and adjacent to the L4/L5 disc interface from an posteriorperspective. More detailed views of the refractor are shown in theadditional panels of FIG. 14.

Of course a wide range of possible combinations of retractor componentsis available in accordance with the disclosure, and may be selected fromthe specific embodiments of arrays as disclosed herein and fromembodiments that are within the scope of the disclosure though notspecifically described in the specification and drawings.

Thus, in various embodiments according to the disclosure, there isprovided a medical device for performing surgery at a surgical fieldwithin a body, the medical device comprising a modular surgicalretractor comprising, a retractor body and a retractor hood, theretractor body and retractor hood each comprising a proximal end that isadapted to extend outside of the surgical field and a distal end that isadapted to extend into the surgical field, the body and hood engageableto form a through channel disposed between open proximal and distal endsbounded by the body and retractor hoods, the through channel having acentral channel axis and the retractor body comprising a floor extendingalong a retractor body longitudinal axis, and the retractor hoodcomprising a body extending along a refractor hood longitudinal axis,the retractor hood having a soft tissue elevator at the distal end, anda releasable handle at the proximal end.

According to some such embodiments, each of the retractor body andretractor hood are independently operable to manipulate soft tissue andadapted to be adjustably and releasably coupled at their proximal endswith general alignment of their respective longitudinal axes, theretractor body and the retractor hood each comprising at its proximalend a coupling element for adjustably and releasably coupling the bodyand hood, one of the coupling elements comprising one or a plurality offasteners, and the other of the coupling elements comprising one or aplurality of receivers. When uncoupled, the retractor hood can bealigned with the retractor body and at least partially compressedagainst the retractor body, and when coupled, the retractor body andretractor hood are displaced from one another vertically and constrainedto one or more of three degrees of freedom, being movable pivotallyaround a pivot axis at the proximal end that is essentiallyperpendicular to the channel longitudinal axis, displaceable verticallyfrom between a compressed orientation up to a pre selected displacementdistance, or slidable horizontally along the channel longitudinal axis,or combinations of these.

In various embodiments, the refractor body is either rectilinear orcurvilinear along its longitudinal axis.

In various embodiments, the retractor body is substantially curvilinearalong its longitudinal axis and has a radius of curvature from about 5to 50 cm. In various embodiments, the distal end of one or both theretractor body and retractor hood is contoured and wherein the contourdescribes a concave arc that transects the retractor's longitudinal axisand has a radius of curvature from about 0.5 cm to 10 cm, and whereinthe contour is bounded by bosses.

In various embodiments, each of the retractor body has a lengthdimension that is greater than, equal to, or smaller than the lengthdimension of the retractor hood.

In various embodiments, the refractor hood is rectilinear along itslongitudinal axis, and is either rectilinear or bowed around itslongitudinal axis along at least a portion of its length.

In various embodiments, the soft tissue elevator at the distal end ofthe retractor hood is either or both recessed relative to an externalsurface of the hood, and has a width dimension that is less than a widthdimension of the proximal end of the hood.

In various embodiments, the refractor body comprises two opposingsidewalls bounding the floor along at least part of the length of thefloor, the floor and sidewalls extending along the longitudinal axis anddefining a chute with an open top, wherein the retractor body sidewallsare selected from essentially planar and bowed. In some suchembodiments, the retractor body sidewalls extend along the longitudinalaxis from the proximal end of the retractor body and terminate proximalto the distal end of the retractor body. In some such embodiments, thesidewalls extend less than half a length dimension of the retractorbody.

In various embodiments each of the retractor body and the retractor hoodhas a width dimension that is generally perpendicular to and runssubstantially along its longitudinal axis; and wherein the width of atleast the distal portion of the retractor hood is less than the width ofthe retractor body such that the retractor hood can be at leastpartially recessed within the chute of the retractor body. In some suchembodiments, the width of the retractor hood from its proximal to itsdistal end is less than a narrowest width of the retractor body suchthat the retractor hood can be fully recessed within the chute of theretractor body and compressed against the refractor body floor.

In various embodiments, the refractor hood comprises hood sidewallsextending along the longitudinal axis at least part of a length of thehood, and wherein the retractor hood has an external height dimensionthat is bounded by an exterior surface of the retractor hood and a hoodsidewall edge. In some such embodiments, the hood sidewalls extend alongthe longitudinal axis from the proximal end of the retractor hood andterminate proximal to the distal end of the retractor hood. In some suchembodiments, the hood sidewalls extend less than half the lengthdimension of the hood.

In various embodiments, the one or more coupling element fasteners is apin oriented along the pivot axis at the proximal end of the retractorhood and the one or more coupling element receivers is an slot orientedin parallel with the common longitudinal axis, the pin(s) slidablyengagable in the slot(s) to couple the hood and the retractor. In somesuch embodiments, the coupling element fasteners comprise a pair of pinson the retractor hood and wherein the coupling element receiverscomprise a pair of slots on the retractor body, each slot comprising aslot opening and a slot seat.

In some embodiments, each of the hood and the body comprise couplingelement fasteners and each engages with a yoke component comprisingreceivers for each of the hood and body fasteners, such that each of thebody, yoke and hood components may be assembled sequentially, or thebody and yoke may be preassembled and receive the hood, or the hood andyoke may be preassembled for attachment to the body. In some suchembodiments, the yoke comprises receiver channels for pin fasteners onthe retractor body and receiver slots for tab fasteners on the hoodbody, and wherein the receiver channels slots are lockable andreleasable, and wherein the yoke comprises a secondary yoke, and whereinwhen coupled, the proximal ends of the retractor body and retractor hoodare displaced from one another vertically, and wherein the receiverchannels and pin fastener are engageable to allow for slidablehorizontally adjustment of the hood position relative to the body alongthe channel longitudinal axis, and wherein the secondary yoke allows foradjustment of the retractor hood around a pivot axis at the proximal endthat is essentially perpendicular to the channel longitudinal axis toenable vertical displacement of the distal end of the hood from thedistal end of the body.

In various embodiments, at least one of the retractor and the hoodcomprises at least one tissue fixation member, comprising a retractorsecurement element and a tissue securement element, the retractorsecurement element securable to one or both of the retractor body andretractor hood, and the tissue securement element securable to a targettissue in the surgical field and selected from a screw, a pin, a wire,an awl, and a tang.

In some embodiments, the securement element is a tang having a proximaland a distal end and is slidable within a channel in the floor of theretractor body, the tang comprising one or both a grasping tab at itsproximal end and a serrated blade that is either curved or pointed atits distal end, the length of the tang being selected from a pluralityof tang lengths.

In other such embodiments, the securement element is a screw, the devicefurther comprising a screw placement guide securable to either the hoodor the body, and a driver engageable with the guide.

In some embodiments, the medical device comprises a lockable channelexpander for adjusting the proximal end vertical displacement of theretractor hood from the open top of the retractor body when theretractor hood and retractor body are coupled.

In various embodiments of the medical device one or both the retractorbody and retractor hood comprises at its proximal end a handle featureselected from a fixed and a releasable handle, and wherein the handle isoriented relative to the retractor at an angle that is between 5 and 90degrees, and wherein the retractor body comprises at its proximal endone or more of a light source attachment, a scope attachment, and atleast one support bracket adapter for attachment to a support bracketfixture that is remote from the surgical field.

In some embodiments, the medical device comprises a distal retractorshim, the shim comprising an elongate shim extender, a proximal grip anda distal shim element having a retractor hood contact surface and aretractor body contact surface, the distance between which surfacesestablishes a shim height.

In some specific embodiments according to the disclosure, there isprovided a medical device for performing minimally invasive surgery in asurgical field, comprising a modular surgical portal comprising, aretractor body and a retractor hood, each of the body and hood having aproximal end that is adapted to extend outside of a surgical field and adistal end that is adapted to extend into the surgical field, and eachof the body and hood being independently operable to manipulate softtissue and adapted to be adjustably and releasably coupled at theirproximal ends in a generally parallel orientation along respectivelongitudinal axes to form an elongate through channel disposed betweenopen proximal and distal ends of the portal, the through channel havinga central portal channel axis. According to some such embodiments, theelongate refractor comprises a floor and two opposing sidewalls thatextend along a longitudinal axis and define a chute with an open top,and the retractor hood comprises, a body extending along a longitudinalaxis, and a soft tissue elevator at the distal end, and a guide handleat the proximal end.

According to some such embodiments, each of the retractor and hoodcomprising a width dimension that is generally perpendicular to itslongitudinal axis, the width of the hood being less than the width ofthe retractor such that the hood can be at least partially recessedwithin the chute of the retractor when they are aligned along thechannel longitudinal axis. According to some such embodiments, at leastthe refractor body is curvilinear and has a radius of curvature of about5 cm to about 25 cm.

According to some such embodiments, each of the retractor and hoodcomprises at its proximal end a coupling element, one of the couplingelements on the retractor and hood comprising one or a plurality offasteners, and the other of the coupling elements on the retractor andthe hood comprising one or a plurality of receivers, the portalcomprising a channel expander for adjusting displacement of the hoodfrom the open top of the retractor when the retractor and hood arecoupled to form the portal.

According to some such embodiments, when coupled, one or both theretractor and hood can be articulated pivotally at the proximal end ofthe portal around a pivot axis that is essentially perpendicular to thecommon longitudinal axis. According to some such embodiments, one orboth the retractor and hood can be slidably displaced along a path thatis essentially parallel with the common longitudinal axis, and thethrough channel can be expanded or contracted by actuating the channelexpander to achieve displacement of the hood from the retractor.

According to some such embodiments, at least one of the retractor andthe hood comprises at least one tissue fixation member, comprising aportal securement element and a tissue securement element, the portalsecurement element securable to the surgical access portal, and thetissue securement element securable to the target tissue site andselected from a screw, a pin, a wire, an awl, and a tang.

Incision Guidance

Referring again to the drawings, FIG. 15 is a schematic showing anincision guidance instrument in accordance with the disclosurepositioned relative to a portion of human anatomy. The instrument isuseful, in particular, for aiding in the selection of incision site on apatient, particularly on a patient in a prone position for whom alateral mode of access to a spinal vertebra or vertebral space isdesired. The guidance instrument includes a support base formed ofessentially radio translucent material. In the depicted embodiment, thebase is generally square or rectangular to aid in the orientation ofpositioning and is embedded with crosshair-oriented position indicators.When the base is placed in the intended orientation relative to thetarget tissue, such as the spine, the position indicators extend insuperior to inferior and transecting lateral dimensions and are formedof radio opaque material. The instrument also includes a verticallyadjustable depth indicator that extends from an upper surface of thesupport base and is desirably formed of essentially radio-translucentmaterial.

In various embodiments, the depth indicator includes a verticallytranslatable extender with graduated markings in conventional units ofmeasure, or alternatively markings indicating a predetermined positionrelative to a position of the patient's anatomy. The extender mayinclude an extender lock. The guidance instrument also includes avertically adjustable and substantially linear pivot arm that extends onan axis that is parallel to the lateral dimension of the positionindicators and is adjustable and lockable vertically. In the depictedembodiment, the pivot arm is attached at a first end to the verticalextender and pivots from a position that is parallel with the extenderto a position that is perpendicular to the extender and parallel to theplane of the base. In various embodiments, the pivot arm has an arcuatepointer extending from a free end of the pivot arm. The arcuate pointeris formed of radio opaque material, allowing its detection byradiography, such as for example, X-Ray fluoroscopy. The arcuate pointeris attached to the pivot arm, and may be adjustably attached to enableadjustable extension therefrom. The guidance instrument may alsocomprise a support bracket adapter for attachment to a support bracketfixture that is remote from the surgical field.

In some embodiments, the guidance instrument may include a through holein the base which would allow passage of a substantially cylindricalinstrument there through. For example, in some embodiments, the guidanceinstrument has a removable vertical extender that can be replaced with aneedle, probe or Jamshidi type device that can affix either directly orthrough the skin to a spinal structure, such as a spinous process on avertebra. In some embodiments, the inserted instrument can be fixed tothe base and the pivot arm attached thereto. In other embodiments, theinstrument can be removed after it is used, for example, to directlydetermine the depth of soft tissue from the surface of the skin to thebony structure. According to such embodiments, the removed instrument isreplaced with the vertical extender. FIG shows alternate back, front,top, bottom, first and second side, and oblique views of an incisionguidance instrument in accordance with the disclosure.

One of ordinary skill will appreciate that the overall shape of the basemay be varied so long as the relevant orientation of the indicators isevident, and that the indicators may be affixed and removable from thebase rather than being embedded therein. It will also be appreciatedthat the guidance instrument may be used for other surgical contextsbeyond the spine, taking advantage of the device's features to identifya desired position within a patient relying on the geometricrelationship of the indicators and the arcuate pointer to select anincision site.

In use, the guidance instrument is positioned on the surgical subjectand under fluoroscopy to confirm collinear alignment of one or moreindicators with target tissue. For example, AP fluoroscopy is used toconfirm collinear alignment of one or more indicators with the spinealong the sagittal plane, and lateral alignment with the target discspace along the transverse plane. FIG. 17 shows in panel A aradiographic image from a human model showing an anterior to posterior(AP) view of a human spine over which is positioned on the patient anincision guidance instrument.

In various embodiments, the height of the vertically adjustable extenderis selected to enable travel of the incision guidance instrument pivotarm along the desired radius of curvature whereby the arcuate pointerwould enter the disc space adjacent to a vertebra of interest at aposition that is dorsal to the midline of the disc along the frontalplane, at approximately 30% of the overall disc height (in the APdimension) from the posterior disc margin, wherein the disc height ismeasured radiographically, for example using CT radiography, as thedistance between the anatomical posterior and anterior disc margins.

It will be appreciated that the locus of entry into the disc space inthe AP dimension is selected based upon the particular anatomicalfeatures of a human spine and the dimensions of the retractorcomponents. Thus, it will be further appreciated that in otherembodiments, the entry point for achieving centering relative to targettissue, including the spine, may be varied so as to achieve desiredpositioning, and the disclosed entry point of entry at a position thatis dorsal to the midline of the disc along the frontal plane, atapproximately 30% of the overall disc height (in the AP dimension) fromthe posterior disc margin is non limiting.

Thus, in other embodiments wherein access to the spine is desired, theentry position may be more dorsal or more ventral, and may be anywherewithin the range from 1% to 99% of the overall disc height from theposterior disc margin, including 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66,67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84,85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, and 99%.

More particularly, the height of the attachment point of the pivot armto the vertically adjustable extender is determined based on one or moreanatomical measurements obtained radiographically or manually relativeto a vertebra of interest, including one more of a spinous process,anterior and posterior vertebral margins, and associated disc margins.According to some such embodiments, the measurements are selected fromdistance from a skin surface above the spinous process to the spinousprocess, distance from the top of the spinous process to the anteriormargin of the disc, and distance from the top of the spinous process tothe posterior margin of the disc.

Once the height of the pivot arm is set, lateral fluoroscopy is used toconfirm the contact point of the arcuate pointer at the center of thedisc space in the SI dimension, and is point of contact on an externalsurface of the subject's skin is selected as the incision site. FIG. 17shows in panel B a radiographic image from a human model showing alateral view of a human spine over which is positioned on the patient anincision guidance instrument, the image showing the orientation of theactuate pointer of the arm of the guidance instrument relative to anintervertebral disc space and the overlying skin surface for determiningincision location

In various embodiments of the guidance instrument the arcuate pointerhas a radius of curvature from about 5 to 50 cm, including 5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,45, 46, 47, 48, 49 and 50, and incremental fractions thereof including0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 cm.

Thus, in various embodiments according to the disclosure, there isprovided a guidance instrument for selecting an incision site for accessto the spine of a surgical subject, comprising a support base formed ofessentially radio translucent material and comprising crosshair-orientedposition indicators that extend in superior to inferior and transectinglateral dimensions and are formed of radio opaque material and avertically adjustable depth indicator that extends from an upper surfaceof the support base and is formed of essentially radio-translucentmaterial.

In various embodiments, the depth indicator comprises a verticallytranslatable extender with graduated markings in conventional units ofmeasure, an extender lock, a vertically adjustable and substantiallylinear pivot arm that extends on an axis that is parallel to the lateraldimension of the position indicators and is adjustable and lockablevertically and which is attached at a first end to the extender andpivots from a position that is parallel with the extender to a positionthat is perpendicular to the extender. In various embodiments, the pivotarm comprises an arcuate pointer extending from a free end of the pivotarm and formed of radio opaque material, the arcuate pointer adjustablyattached to the pivot arm to enable adjustable extension therefrom, and,a support bracket adapter for attachment to a support bracket fixturethat is remote from the surgical field.

In use, the guidance instrument is positioned on the surgical subjectand under AP fluoroscopy to confirm collinear alignment with the spinealong the sagittal plane and lateral alignment with the target discspace along the transverse plane, and the vertical height of the pivotarm is selected to approximate centerline of the disc space andvisualize with lateral fluoroscopy to confirm whereby the contact pointof the arcuate pointer on an external surface of the subject's skin isselected as the incision site.

In various embodiments of the guidance instrument the arcuate pointerhas a radius of curvature from about 5 to 50 cm, and the height of thevertically adjustable extender is determined based on one or moreanatomical measurements obtained radiographically or manually relativeto a vertebra of interest, including one more of a spinous process,anterior and posterior vertebral margins, and associated disc margins.According to some such embodiments, the measurements selected fromdistance from a skin surface above the spinous process to the spinousprocess, distance from the top of the spinous process to the anteriormargin of the disc, and distance from the top of the spinous process tothe posterior margin of the disc. In various embodiments, the height ofthe vertically adjustable extender is selected to enable travel of theincision guidance instrument pivot arm along the desired radius ofcurvature whereby the arcuate pointer would enter the disc spaceadjacent to a vertebra of interest at a position that is dorsal to themidline of the disc along the frontal plane, at approximately 30% of theoverall disc height from the posterior disc margin.

Surgical Access System

In various embodiments according to the disclosure, use of the retractordevice and other system tissue preparation instruments involves the useof other instruments, including tissue retraction and tissue dilationinstruments. Thus, among the suite of available instruments some or allof which may be selected for use by a user, and are provided in thisdisclosure. Referring now to FIG. 18, tissue retraction instruments areshown that include an expandable bilateral speculum, a hand held hoodretractor, a hand held speculum shoehorn, a tang awl, and a ribbonblade. Referring now to FIG. 19, tissue dilation instruments are shownthat include interfitting first and second dilator components and awl.FIG. 29 shows alternate views of the dilator, tang awl and ribbon bladeinstruments.

In use, the tissue dilation instruments are used to achieve successivelygreater dilation of soft tissue as may be deemed appropriate by thesurgeon. Further, the instruments inter-engage with the retractorcomponents along the trajectory of the selected radius of curvature toachieve ideal positioning of the instruments at the target tissue. Thus,in use, the first dilator is suitable to establish engagement at thetarget tissue at the entry position of 30% of the disc height from theposterior disc margin. Thereafter, each of the instruments is usedsuccessively to engage and provide a path for achieving lateral accessto the spine.

Placement of the ribbon blade ventral to the first dilator establishes asmooth path for the passage of the second dilator which inter-engageswith the first dilator and aids in further spreading the soft tissue atthe target site. Insertion of the tang awl through the receiving channelin the second dilator enables controlled guidance of the piercing tip ofthe awl into the ventral aspect of the annulus at the target disc,dorsal to the anterior disc margin, and in various embodiments the tangawl insertion position may be from between 1% and 20% or more of thetotal disc height from the anterior disc margin, including 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20%.Advantageously, the tang awl establishes the initial entry point for atang, which may be used as tissue securement component. Subsequentinsertion of the retractor body adjacent and ventral to the seconddilator/tissue dilation assembly positions the distal end of theretractor body relative to the disc space, and the path of the tang awlensures precise positioning of the tang within the annulus. Uponwithdrawal of the dilation assembly from the incision, SI and APradiography can be used to confirm the proper orientation of theretractor body relative to the disc space and SI radiography can be usedto confirm that the tang is substantially parallel to the anteriorannulus.

As described herein above in connection with embodiments of theretractor, the retractor components and related instruments may becurvilinear or rectilinear, and those that are curvilinear have a radiusof curvature that ranges from 5 to 60 cm or more. It will be appreciatedby one of skill that the radius of the retractor and other instrumentsis influenced by the selected radius of curvature for achieving lateralaccess to the disc space. Generally, the greater the radius, the flatterthe channel and instruments, dictating a more ventral incision site onthe patient, and the smaller the radius, the steeper the channel andinstruments, dictating a more dorsal incision site on the patient.

Without being limiting, the radius of curvature of instruments accordingto the disclosure, particularly the ribbon blade, the first and seconddilators and interfitting tang awl, the hand held speculum, and otherinstruments not specifically disclosed herein that may be adapted fromconventional rectilinear profile for use with the inventive retractor,may be within a range from about 0 cm to about 60 cm or more, and moreparticularly from about 5 cm to about 25 cm, and in some embodiments theradius may be selected from one of 15 cm, 17 cm, 17.5 cm, 18 cm, 22 cm,22.5 cm, and 25 cm. Of course other radii are possible within the rangefrom 0 cm to more than 60 cm, including 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, and 60, andincremental fractions thereof including 0.1, 0.2, 0.3, 0.4, 0.5, 0.6,0.7, 0.8, 0.9 cm.

Selection of and some optional representative uses for the instrumentsare further described herein in connection with the description ofsurgical techniques. One of ordinary skill will appreciate that otherconventional and functional surgical instruments may be used inconnection with the devices and systems and techniques disclosed herein,and the identified instruments are not exclusive and are not limited orlimiting.

Thus, in various embodiments according to the disclosure, there isprovided a surgical system for preparing soft tissue for a surgicalprocedure within a patient. The surgical system comprises a tissuedissection system comprising one or more of a hand held speculumshoehorn, a hand held retractor, an expandable bilateral speculum, atang awl, a tissue dilation system comprising interfitting retractor anddilator components. According to some such embodiments, the dilatorcomponents are selected from two or more of, at least one retractor bodyand at least one retractor hood, a ribbon blade, a first dilator that isreceivable within a second dilator, a second dilator that interfits withthe first dilator and is receivable within the retractor body, an awlreceivable within the second dilator, each of the interfitting retractorand dilator components having a proximal end that is adapted to extendoutside of the patient and a distal end that is adapted for contact withthe target tissue.

According to some specific embodiments, the medical system comprises aretractor body and a retractor hood; a ribbon blade having at itsproximal end at least one support bracket adapter for attachment to asupport bracket fixture that is remote from the surgical field; a seconddilator adapted to be slidably received adjacent to the retractor bodywithout interference, and comprising a first channel for slidablyreceiving a first dilator with an clearance fit and a second channel forslidably receiving an awl with an clearance fit, a first dilator; and anawl. According to some such embodiments, each of the first and seconddilators comprise grip features for attaching an external instrument toguide, orient or drive insertion into tissue, the awl comprises a distalblade and a releasable hand actuator for driving the distal blade intotissue. According to some such embodiments, the medical system alsocomprises a hand held speculum shoehorn, a hand held refractor, anexpandable bilateral speculum, each of the instruments adapted forindependent manual control for manipulation and dissection of softtissue.

Example 1 Representative Surgical Technique

With reference now to the drawings, in particular FIG. 20-FIG. 24C, arepresentative embodiment of a surgical technique includes the followingsteps, the order of which is not intended to be limiting:

Position the Patient

Position patient prone (and generally parallel to the floor) on suitablesurgical table.

Establish Incision Site

Obtain CT scan to measure ventral to dorsal height of target vertebralspace.

Radiographically or directly measure with a needle or wire the posteriorsoft tissue depth to spinous process over target disc space. (Ifprocedure is open, this step is not required.)

Calculate total ventral to dorsal height, and adjust incision guidanceinstrument guide height to enable direction of incision guidanceinstrument pointer to a position that is approximately 30% of theoverall disc height from the posterior disc margin, based on thecalculated disc height. (This is the target entry point into the discspace, dorsal to the midline of the disc along the frontal plane.) Restexemplary represented instrument for measurement (“incision guidanceinstrument”) on patient (either on soft tissue for a closed procedure,or on spinous process if procedure is open) and use position indicatorsto roughly align with the spinal axis. Visualize with AP fluoroscopy toconfirm collinear alignment with the spine along the sagittal plane andlateral alignment with the target disc space along the transverse plane.Engage incision guidance instrument pivot arm to approximate centerlineof the disc space and visualize with lateral fluoroscopy to confirm. Asneeded, adjust fluoroscope position to achieve complete alignment of theimage path and the incision guidance instrument, as confirmed in thefluoroscopy image. Mark skin to indicate cranial to caudal spinalmidline, position of incision guidance instrument on the patient, andincision site to enable access at the target disc entry point.

Incision and Soft Tissue Dissection

Incise skin in a dorsal to ventral orientation, an exemplary incisionwidth being approximately 4 cm. Using a Bovie, dissect through thesubcutaneous tissue and muscles, and puncture through the Transversalisfascia into the retro peritoneum with a Kelly clamp. Manually enlargethe fascia incision and dissect the retro peritoneum towards psoasmuscle, palpating the transverse process to confirm the posterior marginof disc space. Optionally, insert and engage retraction instrument(s),such as a bilateral speculum, in a cranial to caudal orientation tofurther expand the surgical field and expose the spine and associatedsoft tissue. Manually confirm nerve position relative to the psoasmuscle to establish dissection point, and provisionally dissect.

Insert retraction instrument(s) in a ventral to dorsal orientation,inserting a hand held hood retractor with its base oriented to theventral aspect of the incision and insert hand held speculum shoehornoriented to the dorsal aspect of the incision to visualize the lateralpsoas (FIG. 20). Remove cranial to caudal retractor(s) bilateralretractors, if used. While maintaining posterior soft tissue distractionwith the hand held speculum shoehorn, introduce an awl and pass throughthe provisionally dissected psoas muscle to pierce the ipsalateralannulus (FIG. 21A). Optionally, under lateral visualization, confirm awlinsertion at the 30% target entry point relative to the posterior discmargin. Insert a first dilator to complete dissection of the psoas andpenetrate the pierced annulus, optionally under lateral visualization(FIG. 21B). Insert ribbon blade toward the ventral aspect of theincision and below the first dilator. Position the distal end of theribbon blade proximate to the anterior margin of the disc space andcentered on the disc between the vertebrae to initially retract the softtissue ventrally (FIG. 21C). Optionally, affix the ribbon blade to thetable arm to retain tissue retraction (FIG. 22B).

Optionally, place a measuring instrument (e.g., rule or tape measure) onpatient to measure the distances from the spinal midline mark to thecenter of the first dilator and the ribbon blade. Select retractor bodysize (for example, small, medium or large). Insert a second dilatorbetween the first dilator and the ribbon blade, slidably engaging itwith the first dilator (FIG. 21D).

Insert a tang awl into engagement with the second dilator and passtoward the disc space to pierce the ipsalateral annulus, dorsal to theanterior disc margin, with the awl blade piercing the annulus at a pointthat is approximately 30% of the disc height from the posterior discmargin (FIG. 22A and FIG. 22B).

Position and advance the retractor body between the second dilator andthe ribbon blade. Under fluoroscopy, confirm insertion of the removabletang through the annulus at a point that is approximately 30% of thedisc height from the posterior disc margin, thereby establishing a pathwhereby the centerline of the disc (50% from each of the posterior andanterior disc margins) is aligned with the centerline of the channelformed by the retractors (FIG. 23A). Remove the first and seconddilators (FIG. 23B). Insert the hood retractor into the retractor bodyand advance towards the disc space and into contact with the disc justventral to the transverse process (FIG. 24A). Manipulate the proximalend of the hood retractor to engage the psoas muscle, refracting it in adorsal direction by raising the hood to increase separation between thehood retractor and retractor body (FIG. 24B). Engage the mating featuresof the hood and retractor body components at their proximal ends. Adjustthe lateral position of the hood retractor by moving it proximally ordistally to retain elevation of the psoas and avoid compression with thetransverse process. Lock the retractors in the selected position. Removethe ribbon blade, and optionally affix the retractor body to the tablearm (FIG. 24D). Optionally, engage a tissue fixation element, forexample a screw or pin, to enhance engagement with one or bothvertebrae.

At any time during the dissection of the psoas or placement of therefractor components, a stimulator may be placed in the wound and tissuestimulated to monitor for nerves (FIG. 24C). Likewise, at any time theanterior to posterior position of the hood retractor may be adjusted torelive any degree of compression on the spinal nerves.

Example 2 Representative Surgical Technique

According to the foregoing disclosure, in various embodiments, there isprovided a method for performing a surgical procedure on the spine of apatient, the method comprising: opening the surgical field through anincision that is substantially posterior, dissecting soft tissue toinitially contact and visualize a target vertebra, placing a firstretractor within the surgical field to retract soft tissue, theretractor having a distal end positioned substantially adjacent to theanterior aspect of the spine at the intervertebral space between thetarget vertebra and an adjacent vertebra. According to such embodiments,the method also comprising sliding into the surgical field adjacent tothe first refractor a second retractor, the second retractor having adistal end that is adapted for manipulating soft tissue, manuallydirecting the second retractor towards the spine and verticallydisplacing the second retractor posteriorly and away from the firstretractor so as to lift the soft tissue posteriorly/dorsally to enhancevisualization of the spine, assembling the first and second retractorsinto engagement by coupling complimentary coupling elements at proximalends of the retractors, adjusting the coupled retractors in one or moreof three degrees of adjustment and reversibly locking the coupledretractors to establish a channel to the spine.

According to some such embodiments, when coupled retractors aredisplaced from one another vertically in a first plane along a channellongitudinal axis and constrained to one or more of three degrees offreedom, being movable pivotally around a pivot axis at the proximal endthat is essentially perpendicular to the channel longitudinal axis,displaceable vertically to a pre selected displacement distance, orslidable horizontally along the common longitudinal axis, orcombinations of these. According to various embodiments, the patient isin a prone position, and at least one of the retractors is curvilinear.

Instrument for Tissue Preparation

This disclosure provides a suite of tissue manipulation instruments thatenable access to and manipulation of tissue with minimal invasion oftissue, and in certain embodiments, these instruments reduce oreliminate the percussive techniques that are common in most spinalsurgeries. Of course, it will be understood that the instruments may beadapted for use in surgeries other than on the spine of an animal, andwhile representative embodiments are shown as curvilinear, otherrectilinear embodiments are encompassed within the scope of theinvention and may be useful for spinal and other applications.

Referring again to the drawings, FIG. 30 shows alternate views of atissue preparation instrument that comprises a strike plate forintroducing a tissue manipulator component, the represented componentbeing a blade. FIG. 31B shows an alternate embodiment of instrument witha tissue manipulator cutting blade attachment and a second tissuemanipulator in the form of parallel elongate blades for distraction ofthe disc space, wherein the drive for insertion is a rotating screw. Asshown, the instrument includes a tissue penetrating blade that is usedfor cutting through soft tissue, particularly the annulus of a spinaldisc. The blade may be attached by a variety of means, and in someembodiments may be permanently affixed to the device, which is thusdedicated to cutting. In alternate embodiments, the cutting blade isremovable and interchangeable with other blades, box cutters, andscrapers, each of which interchangeable bladed tissue manipulators maybe varied in shape, length, and height. Thus, the disclosure is notlimited to the cutting blades described herein and shown in thedrawings.

Referring now to FIG. 32, alternate views of another tissue preparationinstrument is shown, the instrument comprising the drive system shown inFIG. 31B with an alternate tissue manipulator in the form of aninterbody implant.

Tissue preparation instruments according to the disclosure includeproximal ends that include drive components and distal ends that includetissue engagement components that include one or more tissuemanipulators. The proximal end extends out of the surgical field and thedistal end is insertable in the surgical field. In various embodiments,a tissue preparation instrument has a drive mechanism to drive distaland proximal movement of the insertion assembly for manipulating targettissue. In some embodiments, the drive mechanism is selected from aratchet or gear system comprising one or more rack and pinioncomponents, a walking beam and plates drive system, and, a threaded rodwith a shift for providing rotational force. In some threaded rodembodiments, the drive component includes a threaded element affixed tothe housing that is adapted to receive and engage with the threaded rod.In some such embodiments, the threaded element is a threaded bore.Rotation of the insertion rod within the threaded element results inmovement of the insertion rod in one or the other of the distal orproximal directions. Engagement of a second tissue manipulator, such asfor example, and implant directly or indirectly to the universal jointensures that the tissue manipulator does not rotate when the insertionrod is rotated. Other known free-rotational or swivel mechanisms may beemployed as alternatives to the universal joint.

As described herein above in connection with embodiments of theretractor, the retractor components and related instruments may becurvilinear or rectilinear, and those that are curvilinear have a radiusof curvature that ranges from 5 to 60 cm or more. In accordance with thedisclosure, at least the tissue engagement components of the tissuepreparation instruments hereof may be either rectilinear or curvilinear.According to embodiments wherein the tissue engagement components arecurvilinear, without being limiting, the radius of curvature of may bewithin a range from about 0 cm to about 60 cm or more, and moreparticularly from about 5 cm to about 25 cm, and in some embodiments theradius may be selected from one of 15 cm, 17 cm, 17.5 cm, 18 cm, 22 cm,22.5 cm, and 25 cm. Of course other radii are possible within the rangefrom 0 cm to more than 60 cm, including 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, and 60, andincremental fractions thereof including 0.1, 0.2, 0.3, 0.4, 0.5, 0.6,0.7, 0.8, 0.9 cm.

In various embodiments, the tissue manipulators according to theinvention may include a housing that at least partially encloses all ora portion of each of the drive components and tissue engagementcomponents. In some embodiments, the housing may be formed of an openframe, a closed frame, one or two pair of opposing slates. A frame maybe all or at least partially curvilinear, and may include one or morefixed or adjustable, integrated or attachable/releasable handles. Arepresentative embodiment of an open frame housing is shown, forexample, in FIG. 30, and a representative embodiment of a framecomprising a pair of opposing slats is shown in FIG. 32 and FIG. 31B. Itwill be appreciated that the function of the housing is to support oneor more of the drive and tissue engagement components in alignment withthe delivery trajectory within a surgical field, including particularlyfor insertion in the channel formed by the modular retractor. Otherhousing configurations are possible and may include combinations.

Tissue manipulators in accordance with the disclosure include cuttinginstruments selected from a single blade, a plurality of blades, and abox shaped blade that has a central void and is rectangular in shape;opposing curvilinear elongated blades, each of the curvilinear bladeshaving a distal end and a proximal end, wherein each of the blades has aradius of curvature from between 5 cm and 60 cm or more, and wherein thedistal ends of the curvilinear blades are translatable from a collapsedorientation wherein the blades touch at least at their most distal ends,to a spread orientation wherein the blades are spread apart and not incontact; a distractor paddle; an implant trial; an endplate scraper; animplant; and a length adjuster frame that is adapted for actuationbetween a plurality of preset lengths to adjust the distance of a tissuemanipulator for extension into the disc space. In some embodiments,tissue manipulator blades may be curved, bent or angled laterally (offthe blade axis) such that they are deflected away from or toward eachother along their lengths or In some such embodiments, at the distalend.

In some embodiments, an adjuster frame is used as an intermediatebetween the tissue manipulator and the driver, the adjuster frame beingreleasably engageable with the tissue manipulator such as throughengagement pins. The adjuster frame may include one or more extensionoptions for increasing the length of the extension of the manipulatorfrom the driver. According to such embodiments that include a firsttissue manipulator that includes a pair of blades, the adjuster frame isadapted to receive the opposing blades such that advancement of theadjuster frame proximal to distal spreads the distal ends of the blades,which aids in distraction of the disc space.

Thus, in various embodiments according to the disclosure, there isprovided a spinal tissue preparation device comprising an insertionassembly having a proximal end that is adapted to extend outside of asurgical field and a distal end that is adapted to extend into thesurgical field, and an actuator attached to the insertion assembly atits proximal end and adapted to engage with the drive component todirect force along the path between the proximal and distal ends, toselectively advance at least one tissue manipulator in a distaldirection, and to withdraw the at least one tissue manipulator in aproximal direction.

According to some such embodiments, the tissue engagement componentcomprises a tissue engagement component comprising at least one tissuemanipulator, and a drive component connected on its distal end to theproximal end of the tissue engagement component, and on its proximal endand to an actuator.

According to some such embodiments, at least the tissue engagementcomponent of the insertion assembly is curvilinear and has a radius ofcurvature from between 5 cm and 40 cm. According to some suchembodiments, the actuator is selected from a strike plate for directingeither distal or proximally oriented concussive force to advance orwithdraw the insertion assembly, a ratchet or gear system comprising oneor more rack and pinion components, a walking beam and plates drivesystem, and, a threaded rod with a shift for providing rotational forceto alternately drive distal and proximal movement of the insertionassembly.

According to some such embodiments, the device also comprises one ormore of an adjustable and releasable stabilization handle forpositioning and stabilizing the tissue preparation device, the handlebeing adjustable and releasable to avoid interference with othersurgical instruments, and a vertical shift component for dorsal toventral vertical adjustment and positional locking of the actuator toavoid interference between components of the insertion assembly and withother surgical instruments.

According to some specific embodiments the actuator comprises a strikeplate, the drive component of the insertion assembly comprises acurvilinear housing that at least partially encloses the tissuemanipulator and at least a portion of the distal end of the actuator,the housing further comprising at its distal end a tissue engagementseat comprising at least a pair of engagement teeth for penetratingtarget tissue and a guide for directing the tissue manipulator intoengagement with the target tissue between the teeth, and comprising anelongate curvilinear push rod engageable at its distal end to the tissuemanipulator and at its proximal end to the actuator, and the tissuemanipulator comprises a cutting instrument releasably attachable to thedrive component, the cutting instrument selected from a single blade, aplurality of blades, and a box shaped blade that has a central void andis rectangular in shape.

In such embodiments a spinal tissue preparation device comprise a firsttissue manipulator that comprises a pair of opposing curvilinearelongated blades, each of the curvilinear blades having a distal end anda proximal end, wherein each of the blades has a radius of curvaturefrom between 5 cm and 40 cm, and wherein the distal ends of thecurvilinear blades are translatable from a collapsed orientation whereinthe blades touch at least at their most distal ends, to a spreadorientation wherein the blades are spread apart and not in contact. Insome embodiments, the drive system is selected from a ratchet or gearsystem comprising one or more rack and pinion components, a walking beamand plates drive system, and, a threaded rod with a shift for providingrotational force to alternately drive distal and proximal movement ofthe insertion assembly.

According to such embodiments, the device comprises one or more of anadjustable and releasable stabilization handle for positioning andstabilizing the tissue preparation device, the handle being adjustableand releasable to avoid interference with other surgical instruments,and a vertical shift component for dorsal to ventral vertical adjustmentand positional locking of the drive system actuator to avoidinterference between components of the insertion assembly and with othersurgical instruments.

According to such embodiments, the device includes a tissue manipulatorattachment element comprising a universal joint attachable to the distalend of the drive system actuator, a frame having distal and proximalattachment ends and blade receiving sidewalls into which each of therespective blades are inserted, the frame attachable at its proximal endto the universal joint, and movable from the proximal to the distal endsof the blades to a terminal position defined by a positive stop on oneor both blades, a releasable tissue manipulator fastener for engagementof a second tissue manipulator selected from a distractor paddle, animplant trial, a cutting instrument, an endplate scraper, and animplant; a length adjuster that is adapted for actuation between aplurality of preset lengths to adjust the distance of the second tissuemanipulator from the frame.

According to such embodiments, in operation, the blades are insertableinto the target tissue in their collapsed orientation with the frame atthe proximal end of the blades, and positive actuation of the drivecomponent directs the frame towards the tissue and expands the blades,driving the second tissue manipulator into contact with the targettissue, and upon further positive actuation, withdrawing the blades fromthe tissue leaving the extended second tissue manipulator within thetarget tissue. And According to such embodiments, negative actuation ofthe drive component withdraws the frame away from the tissue, drawingthe frame toward the proximal end of the instrument and allowing theblades to collapse for easy withdrawal from the surgical field.

According to some embodiments in which a tissue manipulator comprisesblades, each of the blades comprises inner and outer surfaces, and athickness that may be continuous or may vary by narrowing from theproximal to the distal end, each blade having on its outer surface asurface feature to enhance engagement with the surface of tissue.According to such embodiments, the surface feature comprises one or moreof ridges, ribs, knurls, hooks, spikes, teeth, or combinations of these,including one or combinations that are either distal, proximal, neutral,or variably directed.

Example 3 Representative Surgical Technique to Release Disc Space

Insert tape measure into surgical field adjacent to visualized disc todetermine disc height (ventral to dorsal) dimension and initially piercedisc using an elongate scalpel or dissector. Select osteotome bladebased on measured ventral to dorsal height of disc. Insert osteotome andadvance to contact spine. Using a mallet, impact strike-pad on osteotomebody to engage distal opposing teeth with spine (FIG. 25A). Advanceblade distally toward disc and using a mallet, impact strike-pad onosteotome body to advance blade through the discus pulpous toward thecontralateral annulus (FIG. 25B). Confirm progress radiographically.Disengage osteotome from spine and remove from field. Perform annulotomyand basic nuclectomy using selected instruments (pituitary and other).Affix boxcutter blade to osteotome, and insert in to field (FIG. 26A).Using a mallet, impact strike-pad on osteotome body to advance boxcutter through contralateral annulus. Confirm progress radiographically(FIG. 26B). Disengage osteotome box cutter from spine and remove fromfield. Insert a disc-cleaning tool to clear vertebral endplates ofresidual disc material. Remove disc-cleaning tool from field.

Example 4 Representative Distraction and Implant Placement

Select implant (not shown) size based on shim placement (length) andtrials (height). Insert paddle distractor with estimated trial based onmeasurements. Rotate trial to enhance distraction of disc space. Confirmprogress radiographically (FIG. 27A). Place implant inserter device andtrial to confirm implant size. To load the implant and place the implantinserter device: Push release button to disengage threads; Threadimplant onto universal joint by turning the knob at the proximal end;Snap the appropriate size guide collar onto the universal joint;Position the implant in the proximal portion of the squid channel (FIG.27B); Return release button to the flush position to engage the threads;Place implant (FIG. 28A and FIG. 28B), confirming positionradiographically (FIG. 28C).

Example 5 Representative Surgical Technique

In various embodiments according to the disclosure, there is provided amethod for performing a surgical procedure on the spine of a patient,the method comprising, placing a first retractor having a distal endsubstantially adjacent to an anterior aspect of a spine at a targetintervertebral space between a first vertebra and a adjacent vertebra,sliding adjacent to the first retractor a second retractor, the secondretractor having a distal end that is adapted for manipulating softtissue, manually directing the second retractor towards the spine anddisplacing the second retractor posteriorly and away from the firstrefractor so as to lift the soft tissue posteriorly/dorsally to enhancevisualization of the spine, assembling the first and second retractorsinto engagement by coupling complimentary coupling elements at proximalends of the retractors to form a channel between the two retractorshaving a longitudinal axis that runs distal to proximal, adjusting thecoupled retractors pivotally around a pivot axis at their proximal endsto displace the distal ends of the retractors away from one another intoan open position, and locking.

According to such embodiments, the method may also comprise selecting atissue preparation device and fitting it with one of selected tissuemanipulators, and proceeding with one or more of the following steps inthe provided or any other order, including, inserting the tissuepreparation device into the channel and into contact with the targetvertebral space, the tissue preparation device fitted with a cuttinginstrument for penetrating a annulus of a disc within the targetvertebral space, and actuating the drive component to direct the cuttinginstrument into contact with the target vertebral space to penetrate theannulus; actuating the drive component to withdraw and replace thecutting instrument with another cutting instrument for penetrating acontralateral annulus of the disc within the target vertebral space,actuating the drive component to insert the tissue manipulator intocontact with the target vertebral space to penetrate the contralateralannulus.

According to such embodiments, the method may also comprise actuatingthe drive component to withdraw and replace the cutting instrument witha distraction paddle, actuating the drive component to insert the tissuemanipulator into contact with the target vertebral space to deliver thepaddle distractor which is actuated to enhance distraction of theadjacent vertebrae; actuating the drive component to withdraw andreplace the distraction paddle with an endplate scraper, and actuatingthe drive component to insert the tissue manipulator into contact withthe target vertebral space to deliver the scraper which is actuated towithdraw disc material from the disc space.

According to such embodiments, the method may also comprise actuatingthe drive component to withdraw and replace the endplate scraper with animplant trial, and actuating the drive component to insert the tissuemanipulator into contact with the target vertebral space to deliver theimplant trial to determine implant size.

According to such embodiments, the method may also comprise actuatingthe drive component to withdraw and replace the implant trial with animplant, actuating the implant length adjuster to optimize centering ofthe implant in the disc space, actuating the drive component to insertthe tissue manipulator into contact with the target vertebral space todeliver the implant, and actuating the release to deposit the implant inthe vertebral space, and withdrawing the tissue preparation device fromthe channel.

Table Apparatus for Surgical Access

In accordance with the disclosure, methods and devices are disclosedthat enable enhanced access to the spine, most particularly the lowerlumbar region of the spine, for surgical procedures thereon. Includedherein are new designs, additions and enhancements comprising supportssuitable for use with existing surgical table designs that allow formanipulation of a patient's anatomy to maximize access to a surgicalsite of interest, particularly lower lumbar spine access. In someexemplary embodiments, the supports are useful with a patient in a proneposition. The disclosed devices also enable surgical methods that arenot possible using existing table and other support devices.

In exemplary embodiments as shown in the drawings, a support comprisesat least two substantially planar platform elements that are movablerelative to one another and attachable to a table via rails, posts orother means. The relative motion of the platforms is arcuate, and oneplatform pivots in a radius of about 42 inches (based essentially on acircle centered on the feet of the patient extending to the top of thepelvis/iliac crest of the average size person). In various alternateembodiments, the radius may be smaller or greater, and may range from 30inches to 60 inches or more, including 30, 31, 32, 33, 34, 35, 36, 37,38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55,56, 57, 58, 59, and 60 inches or more. In various embodiments, the pivotfrom side to side may vary from about 10 to 60 degrees, and in someembodiments the pivot is about 30 degrees. Thus, the pivot angle may be30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, and 60 degrees.

The coupling mechanism or track between the at least two platformsenables smooth motion along the arc, effected with bearings, wheels orother smooth means of translation. The translation means will beresistant to compressive forces of the patient's pelvis, and will befully adjustable by actuation of the motion control.

In some embodiments, the platform comprises a thigh bolster to hold thehips and thighs in place. In various embodiments, such bolster may havean angulation typical for bolsters known in the art, for example about45 degrees with exemplary dimensions of 6″×6″×6″. Of course, any otherdimensions of bolsters are possible and may be provided at anyangulation, the examples given herein being non-limiting.

Referring now to the drawings, support devices shown in FIG. 33, FIG. 35and FIG. 36 and described herein enable the adjustable positioning andsupport of a patient in a prone position. A pivoting support is providedthat allows for lateral displacement from the spinal midline of aportion of the patient's spine, as illustrated in FIG. 33A. The supportcan be placed, in a representative embodiment, at the hips of thepatient and swung from to one or the other side to enhance access to aparticular spinal region, such as for example L4/L5 vertebral joint.FIG. 34 shows top and end on views of a conventional support table withconventional support components used for the chest, thigh and head of apatient. FIG. 33B shows conventional support table components with anovel lumbar pivot component that provides a lumbar access positionersystem. The pivot support includes at least pad and pivot platforms thatare essentially planar, as shown in FIG. 35. Referring now to FIG. 35A,the support platform includes on a first side for contact with thepatient cushioned material and optional positioning features, asdescribed below. The support platform includes on an opposite side ofthe cushion a pivot surface for engagement with the pivot platform, thepivot surface including engagement features to enable lateral motionwhen actuated. The features are shown in FIG. 35B as curved rails in aparallel array that interface with corresponding tracks on the picotplatform, as shown in FIG. 35C. It will be appreciated that otherengagement features may be used to enable the relative pivotal motionbetween the two platforms, and the disclosed means are not limiting.

In some embodiments, as shown in FIG. 35, the support includes bumpers,either passively contact the patent to stabilize or elevate one or bothsides of the hips. These supports may optionally be actively attached bygripping or straps (not shown) to the patent to selectively secure aportion of the patients anatomy such that when the support is activatedinto motion, the degree of bend is enhanced thus enhancing the degree ofexposure of the spinal region of interest. In accordance with suchembodiments, the one or more supports may include counter supports tosecure the position of the patient's anatomy and prevent counter bendingand reversion to a neutral spinal orientation. In alternate embodiments,features other than bumpers may be used to stabilize and secure thepatient's anatomy to the pivot support, and the disclosed bumpers arenot intended to be limiting.

In some embodiments, the design preserves radiolucency under fluoroscopywhen the table is adjusted, and thus one or more of the supports or itscomponents is radiolucent. In some embodiments the rollers and or railssupporting the supports are also formed of radiolucent material

In various embodiments, the supports are attached in a secure manner tothe table, for example with tracks for receiving table frame rails, thetracks shown in FIG. 35D, and comprise actuators for adjusting thelateral pivot angle. In some embodiments, the supports also includepositive locking elements to avoid inadvertent actuation and preventinjury to the operator or the patient. Further, in various embodiments,the support pivot actuators are lockable, and in some embodimentscomprise positive locking elements to avoid inadvertent actuation. FIG.35E shows a possible locking driver that may be adapted for engagementwith the pivot platform or the support platform to drive relative motionbetween them. The driver may be a pusher/puller with positive lock, or arotary crank with a positive lock, and may further include a gauge thatreflects the degree of rotation of the patient's anatomy from theneutral centerline of the table.

In use, the positioning apparatus is used to enable side-to-siderotation of a body part off the central axis of the table at a selectedangle from a centerline, and fixing that body part to the table frame inorder to maintain position. In some embodiments, the body partpositioned on the apparatus is the pelvis, and in some such embodiments,the tissue to be accessed is the spine. Referring now to FIG. 36A showsin the left frame a patient in prone and neutral (non-rotated) position,and in the right frame a close up anatomical depiction of the spineshowing an assembled retractor according to the disclosure associatedwith the spine at the L4/L5 intervertebral space. It is evident from thedrawing that the position of the patient's left hip relative to theinserted instrument interferes with and throws off the alignmenttherewith. Referring now to FIG. 36B, actuation of the pivot driver byswinging the support platform to the left causes the hip to rotate awayfrom the spine, enhancing access to the vertebral space and enablingmore desirable alignment of the distal end of the retractor assemblywith the spine.

Thus, in various embodiments according to the disclosure, there isprovided an apparatus for positioning a patient during surgery. Invarious embodiments, the apparatus may comprise modular adaptations toconventional surgical surfaces or tables, and in other embodiments maybe a new surface or table. According to various embodiments, theapparatus comprises a pivoting support mountable on a conventionalsurgical table frame. Conventional table frames suitable for adaptationinclude, but are not limited to a surgical table frame comprising two ormore longitudinal rails that are laterally spaced and two or moretransverse rails, and one or more conventional modular body supportsselected from head, chest, abdomen, hip, thigh, and foot supports, whichsupports are removably or permanently fixed on the frame in a generallyplanar orientation, and which may be pivotally or otherwise adjusted tobe above, below or transverse to the common plane. In other embodimentsthe table frame may have another configuration other than rods/rails andmay also comprise more or fewer body supports.

According to the various embodiments of the disclosed apparatus, thepivoting support comprises a support platform, a pivot platform, andsurgical table engagement elements. According to such embodiments, thesupport platform comprises on an upper surface a pad layer for providingcushioned support, two or more opposing bolsters that are laterallyspaced relative to the pad, the bolsters optionally comprising one ormore straps for securing the body position between the laterally spacedbolsters, and comprising on a back surface elements for engagement withthe pivot platform. According to such embodiments, the pivot platformcomprises on an upper surface a plurality of arcuate tracks comprisingengagement elements that are engageable with the engagement elements onthe back of the support platform, and comprising on a back surfaceadjustable and releasable surgical table engagement elements.

According to various embodiments, the pivoting support enablespositional adjustment of a portion of the body resting thereon byrotational movement of the support platform along the path of theactuate tracks of the pivot platform to displace the supported bodyposition in the direction of rotation. In various embodiments, therelative motion of the platforms is arcuate around a radius of curvaturebetween 10 and 100 inches, including between 30 and 60 inches, andincluding a radius of about 42 inches. In various embodiments, thecenterline of the arc is substantially parallel to the patient's spineand the longitudinal dimension of the table, and wherein the pivotplatform is rotated either left or right off the centerline wherein theextent of displacement from neutral position in each direction isbetween 10 degrees and 60 degrees, including between 20 and 40 degrees,and including 30 degrees.

According to various embodiments, the engagement elements for engagementbetween the support platform and the pivot platform are selected frombearings, wheels and inter-fitting rails.

According various embodiments, the pivoting support comprises one ormore of a pivoting actuator for moving the support platform relative tothe pivot platform, the actuator selected from a crank and apusher/puller, a displacement guide for selecting the extent ofdisplacement of the support platform from center along the arc, and alocking element for releasably locking the position of the displacedsupport platform.

According to various embodiments, the relative motion of the platformsis arcuate around a radius of curvature that is adjustably selectableand defined by a circle centered on the feet of the patient extending tothe top of the pelvis/iliac crest.

In some specific embodiments, the pivot platform is selected from anarray of platforms each having plurality of arcuate tracks thatcorrespond with a radius of curvature for a particular patientpopulation, the array including at least one unique radius of curvatureor ranges of radii of curvature, such as for example, small size havinga radius range from 20-30 inches, medium size having a radius range from30-40 inches, and large size having a radius range from 40-60 inches.

While the disclosed embodiments have been described and depicted in thedrawings in the context of the human spine, it should be understood byone of ordinary skill that all or various aspects of the embodimentshereof may be used in in connection with other species and within anyspecies on other parts of the body where deep access within the tissueis desirable.

While various inventive aspects, concepts and features of the generalinventive concepts are described and illustrated herein in the contextof various exemplary embodiments, these various aspects, concepts andfeatures may be used in many alternative embodiments, eitherindividually or in various combinations and sub-combinations thereof.Unless expressly excluded herein all such combinations andsub-combinations are intended to be within the scope of the generalinventive concepts. Still further, while various alternative embodimentsas to the various aspects, concepts and features of the inventions (suchas alternative materials, structures, configurations, methods, devicesand components, alternatives as to form, fit and function, and so on)may be described herein, such descriptions are not intended to be acomplete or exhaustive list of available alternative embodiments,whether presently known or later developed.

Those skilled in the art may readily adopt one or more of the inventiveaspects, concepts and features into additional embodiments and useswithin the scope of the general inventive concepts, even if suchembodiments are not expressly disclosed herein. Additionally, eventhough some features, concepts and aspects of the inventions may bedescribed herein as being a preferred arrangement or method, suchdescription is not intended to suggest that such feature is required ornecessary unless expressly so stated. Still further, exemplary orrepresentative values and ranges may be included to assist inunderstanding the present disclosure; however, such values and rangesare not to be construed in a limiting sense and are intended to becritical values or ranges only if so expressly stated.

Moreover, while various aspects, features and concepts may be expresslyidentified herein as being inventive or forming part of an invention,such identification is not intended to be exclusive, but rather theremay be inventive aspects, concepts and features that are fully describedherein without being expressly identified as such or as part of aspecific invention. Descriptions of exemplary methods or processes arenot limited to inclusion of all steps as being required in all cases,nor is the order that the steps are presented to be construed asrequired or necessary unless expressly so stated.

TABLE 1 SCHEDULE OF FEATURES: Description REF # Modular surgicalretractor 10 Retractor body 20 Proximal end 21, 41 Distal end 22, 42Retractor body floor 23 Retractor body sidewalls 24 Chute 25 Bosses 26Contoured distal end 27, 47 Tang Channel 28 Retractor body longitudinalaxis 29 Retractor hood 40 Retractor hood body 42 Hood sidewalls 44Retractor hood longitudinal axis 45 Lateral Slots 46 Soft tissueelevator 47 Releasable handle flange 48 Coupling element Tab Fastener 52Coupling element Pin Fastener 53 Coupling element Receiver channel 54Coupling element Receiver slot 55 Pivot axis 56 Yoke 60 Through channel64 Central channel axis 68 Tissue fixation 70 A retractor securementelement 72 Tissue securement element 74 Elongate Arm 76 Locking ring 77Driver engageable with the guide 78 Tang 86 Tang grasping tab 82 Tangserrated blade 84 Slidable retractor blade 90 Compressed 100 Displacedvertically 120 Incision guidance instrument 200 Support base 210Crosshair-oriented position indicators 220 A vertically adjustable depth230 indicator Vertical extender with graduated 234 markings Linear pivotarm 240 Arcuate pointer 245 Support bracket adapter 250 Speculumshoehorn 300 Hand held retractor 310 Bilateral retractor 320 Hood handle330 Shim 340 Awl 360 Tissue dilation system 400 Ribbon blade 420 Firstdilator 430 Second dilator 440 Tang awl 460 Tissue preparation device500 Tissue engagement component 510 Tissue manipulator cutting 522instrument Tissue manipulator pair of opposing 530 curvilinear elongatedblades Collapsed orientation 532 A drive engagement component 560Actuator strike plate 562 Actuator rotating handle 566 Elongatecurvilinear push rod 570 housing 600 Tissue engagement seat 610Engagement teeth 612 Guide for directing the tissue 614 manipulatorThreaded rod 620 Drive release button 630 Adjustable and releasable 640stabilization handle A vertical shift component 650 Tissue manipulatorattachment 700 element Universal joint 710 Extender frame 720 Distal andproximal attachment ends 721, 722 Blade receiving sidewalls 724, 726 Areleasable tissue manipulator 730 fastener A length adjuster 732Pivoting support 900 Conventional surgical table frame 910 Longitudinalrails 920 Conventional modular body supports 940 Support platform 950Upper surface pad layer 952 Bolsters 954 Lower surface support platform956 Engagement feature 958 Pivot platform 960 Plurality of arcuatetracks 962 Adjustable and releasable surgical 980 table engagementelements Crank 990

I claim:
 1. A medical device for performing surgery at a surgical fieldwithin a body, comprising: a modular surgical retractor comprising, aretractor body and a retractor hood, the retractor body and retractorhood each comprising a proximal end that is adapted to extend outside ofthe surgical field and a distal end that is adapted to extend into thesurgical field, the body and hood engageable to form a through channeldisposed between open proximal and distal ends bounded by the body andrefractor hoods, the through channel having a central channel axis theretractor body comprising a floor extending along a retractor bodylongitudinal axis, and the retractor hood comprising a body extendingalong a retractor hood longitudinal axis, the retractor hood having asoft tissue elevator at the distal end, and a releasable handle at theproximal end, each of the retractor body and retractor hood beingindependently operable to manipulate soft tissue and adapted to beadjustably and releasably coupled at their proximal ends with generalalignment of their respective longitudinal axes, the retractor body andthe retractor hood each comprising at its proximal end a couplingelement for adjustably and releasably coupling the body and hood, one ofthe coupling elements comprising one or a plurality of fasteners, andthe other of the coupling elements comprising one or a plurality ofreceivers, wherein when uncoupled, the retractor hood can be alignedwith the retractor body and at least partially compressed against theretractor body, and wherein when coupled, the retractor body andretractor hood are displaced from one another vertically and constrainedto one or more of three degrees of freedom, being movable pivotallyaround a pivot axis at the proximal end that is essentiallyperpendicular to the channel longitudinal axis, displaceable verticallyfrom between a compressed orientation up to a pre selected displacementdistance, or slidable horizontally along the channel longitudinal axis,or combinations of these.
 2. The medical device according to claim 1,wherein the retractor body is either rectilinear or curvilinear alongits longitudinal axis.
 3. The medical device according to claim 2,wherein the retractor body is substantially curvilinear along itslongitudinal axis and has a radius of curvature from about 5 to 50 cm.4. The medical device according to claim 1, wherein the distal end ofone or both the retractor body and retractor hood is contoured andwherein the contour describes a concave arc that transects theretractor's longitudinal axis and has a radius of curvature from about0.5 cm to 10 cm, and wherein the contour is bounded by bosses.
 5. Themedical device according to claim 2, wherein the retractor hood isrectilinear along its longitudinal axis, and is either rectilinear orbowed around its longitudinal axis along at least a portion of itslength.
 6. The medical device according to claim 1, wherein theretractor body comprises two opposing sidewalls bounding the floor alongat least part of the length of the floor, the floor and sidewallsextending along the longitudinal axis and defining a chute with an opentop, wherein the retractor body sidewalls are selected from essentiallyplanar and bowed.
 7. The medical device according to claim 1, wherein atleast one of the retractor and the hood comprises at least one tissuefixation member, comprising: a refractor securement element and a tissuesecurement element, the retractor securement element securable to one orboth of the refractor body and retractor hood, and the tissue securementelement securable to a target tissue in the surgical field and selectedfrom a screw, a pin, a wire, an awl, and a tang.
 8. The medical deviceaccording to claim 7, wherein the securement element is a tang having aproximal and a distal end and is slidable within a channel in the floorof the retractor body, the tang comprising one or both a grasping tab atits proximal end and a serrated blade that is either curved or pointedat its distal end, the length of the tang being selected from aplurality of tang lengths.
 9. The medical device according to claim 7,wherein the securement element is a screw, the device further comprisinga screw placement guide securable to either the hood or the body, and adriver engageable with the guide.
 10. A guidance instrument forselecting an incision site for access to the spine of a surgicalsubject, comprising: a support base formed of essentially radiotranslucent material and comprising crosshair-oriented positionindicators that extend in superior to inferior and transecting lateraldimensions and are formed of radio opaque material; a verticallyadjustable depth indicator that extends from an upper surface of thesupport base and is formed of essentially radio-translucent material,the depth indicator comprising a vertically translatable extender withgraduated markings in conventional units of measure, an extender lock; avertically adjustable and substantially linear pivot arm that extends onan axis that is parallel to the lateral dimension of the positionindicators and is adjustable and lockable vertically and which isattached at a first end to the extender and pivots from a position thatis parallel with the extender to a position that is perpendicular to theextender, the pivot arm comprising an arcuate pointer extending from afree end of the pivot arm and formed of radio opaque material, thearcuate pointer adjustably attached to the pivot arm to enableadjustable extension therefrom; and, a support bracket adapter forattachment to a support bracket fixture that is remote from the surgicalfield; wherein, in use, the guidance instrument is positioned on thesurgical subject and under AP fluoroscopy to confirm collinear alignmentwith the spine along the sagittal plane and lateral alignment with thetarget disc space along the transverse plane, and the vertical height ofthe pivot arm is selected to approximate centerline of the disc spaceand visualize with lateral fluoroscopy to confirm whereby the contactpoint of the arcuate pointer on an external surface of the subject'sskin is selected as the incision site.
 11. A guidance instrumentaccording to claim 10, wherein the arcuate pointer has a radius ofcurvature from about 5 to 50 cm, and wherein the height of thevertically adjustable extender is determined based on one or moreanatomical measurements obtained radiographically or manually relativeto a vertebra of interest, including one more of a spinous process,anterior and posterior vertebral margins, and associated disc margins,the measurements selected from distance from a skin surface above thespinous process to the spinous process, distance from the top of thespinous process to the anterior margin of the disc, distance from thetop of the spinous process to the posterior margin of the disc, whereinthe height of the vertically adjustable extender is selected to enabletravel of the incision guidance instrument pivot arm along the desiredradius of curvature whereby the arcuate pointer would enter the discspace adjacent to a vertebra of interest at a position that is dorsal tothe midline of the disc along the frontal plane, at approximately 30% ofthe overall disc height from the posterior disc margin.
 12. A tissuepreparation device comprising: an insertion assembly having a proximalend that is adapted to extend outside of a surgical field and a distalend that is adapted to extend into the surgical field, the tissueengagement component comprising a tissue engagement component comprisingat least one tissue manipulator, and a drive component connected on itsdistal end to the proximal end of the tissue engagement component, andon its proximal end and to an actuator wherein at least the tissueengagement component of the insertion assembly is curvilinear and has aradius of curvature from between 5 cm and 25 cm an actuator attached tothe insertion assembly at its proximal end and adapted to engage withthe drive component to direct force along the path between the proximaland distal ends, to selectively advance at least one tissue manipulatorin a distal direction, and to withdraw the at least one tissuemanipulator in a proximal direction.
 13. A tissue preparation deviceaccording to claim 12, the actuator comprising a strike plate, the drivecomponent of the insertion assembly comprising a curvilinear housingthat at least partially encloses the tissue manipulator and at least aportion of the distal end of the actuator, the housing furthercomprising at its distal end a tissue engagement seat comprising atleast a pair of engagement teeth for penetrating target tissue and aguide for directing the tissue manipulator into engagement with thetarget tissue between the teeth, and comprising an elongate curvilinearpush rod engageable at its distal end to the tissue manipulator and atits proximal end to the actuator, the tissue manipulator comprising acutting instrument releasably attachable to the drive component, thecutting instrument selected from a single blade, a plurality of blades,and a box shaped blade that has a central void and is rectangular inshape.
 14. A tissue preparation device according to claim 12, comprisinga first tissue manipulator comprising a pair of opposing curvilinearelongated blades, each of the curvilinear blades having a distal end anda proximal end, wherein each of the blades has a radius of curvaturefrom between 5 cm and 25 cm, and wherein the distal ends of thecurvilinear blades are translatable from a collapsed orientation whereinthe blades touch at least at their most distal ends, to a spreadorientation wherein the blades are spread apart and not in contact. 15.A tissue preparation device according to claim 14, comprising anactuator selected from a ratchet or gear system comprising one or morerack and pinion components, a walking beam and plates drive system, and,a threaded rod with a shift for providing rotational force toalternately drive distal and proximal movement of the insertionassembly; an optional drive release button to release the drive tomanual proximal to distal insertion and removal; one or more of anadjustable and releasable stabilization handle for positioning andstabilizing the tissue preparation device, the handle being adjustableand releasable to avoid interference with other surgical instruments,and a vertical shift component for dorsal to ventral vertical adjustmentand positional locking of the drive actuator to avoid interferencebetween components of the insertion assembly and with other surgicalinstruments; a tissue manipulator attachment element comprising auniversal joint attachable to the distal end of the actuator, anextender frame having distal and proximal attachment ends and bladereceiving sidewalls into which each of the respective blades areinserted, the frame attachable at its proximal end to the universaljoint, and movable from the proximal to the distal ends of the blades toa terminal position defined by a positive stop on one or both blades, areleasable tissue manipulator fastener for engagement of a second tissuemanipulator selected from a distractor paddle, an implant trial, acutting instrument, an endplate scraper, and an implant; a lengthadjuster that is adapted for actuation between a plurality of presetlengths to adjust the distance of the second tissue manipulator from theextender frame; wherein, in operation, the blades are insertable intothe target tissue in their collapsed orientation with the frame at theproximal end of the blades, and positive actuation of the drivecomponent directs the extender frame towards the tissue and expands theblades, driving the second tissue manipulator into contact with thetarget tissue, and upon further positive actuation, withdrawing theblades from the tissue leaving the extended second tissue manipulatorwithin the target tissue; and wherein negative actuation of the drivecomponent withdraws the frame away from the tissue, drawing the frametoward the proximal end of the instrument and allowing the blades tocollapse for easy withdrawal from the surgical field.
 16. A method forperforming a surgical procedure on the spine of a patient, the methodcomprising: placing a first retractor having a distal end substantiallyadjacent to an anterior aspect of a spine at a target intervertebralspace between a first vertebra and a adjacent vertebra, sliding adjacentto the first refractor a second retractor, the second retractor having adistal end that is adapted for manipulating soft tissue, manuallydirecting the second retractor towards the spine and displacing thesecond retractor posteriorly and away from the first retractor so as tolift the soft tissue posteriorly/dorsally to enhance visualization ofthe spine, assembling the first and second retractors into engagement bycoupling complimentary coupling elements at proximal ends of theretractors to form a channel between the two retractors having alongitudinal axis that runs distal to proximal, adjusting the coupledretractors pivotally around a pivot axis at their proximal ends todisplace the distal ends of the retractors away from one another into anopen position, and locking; selecting a tissue preparation deviceaccording to claim 15 and fitting it with one of selected tissuemanipulators, and proceeding with one or more of the following steps inthe provided or any other order, including: inserting the tissuepreparation device into the channel and into contact with the targetvertebral space, the tissue preparation device fitted with a cuttinginstrument for penetrating a annulus of a disc within the targetvertebral space, and actuating the drive component to direct the cuttinginstrument into contact with the target vertebral space to penetrate theannulus; actuating the drive component to withdraw and replace thecutting instrument with another cutting instrument for penetrating acontralateral annulus of the disc within the target vertebral space,actuating the drive component to insert the tissue manipulator intocontact with the target vertebral space to penetrate the contralateralannulus; actuating the drive component to withdraw and replace thecutting instrument with a distraction paddle, actuating the drivecomponent to insert the tissue manipulator into contact with the targetvertebral space to deliver the paddle distractor which is actuated toenhance distraction of the adjacent vertebrae; actuating the drivecomponent to withdraw and replace the distraction paddle with anendplate scraper, and actuating the drive component to insert the tissuemanipulator into contact with the target vertebral space to deliver thescraper which is actuated to withdraw disc material from the disc space;actuating the drive component to withdraw and replace the endplatescraper with an implant trial, and actuating the drive component toinsert the tissue manipulator into contact with the target vertebralspace to deliver the implant trial to determine implant size; actuatingthe drive component to withdraw and replace the implant trial with animplant, actuating the implant length adjuster to optimize centering ofthe implant in the disc space, actuating the drive component to insertthe tissue manipulator into contact with the target vertebral space todeliver the implant, and actuating the release to deposit the implant inthe vertebral space; withdrawing the tissue preparation device from thechannel.
 17. An apparatus for positioning a patient during surgerycomprising: a pivoting support mountable on a conventional surgicaltable frame, wherein the conventional table frame includes two or morelongitudinal rails that are laterally spaced and two or more transverserails, and one or more conventional modular body supports selected fromhead, chest, abdomen, hip, thigh, and foot supports, the pivotingsupport comprises a support platform; a pivot platform; and, surgicaltable engagement elements, the support platform comprising on an uppersurface a pad layer for providing cushioned support, two or moreopposing bolsters that are laterally spaced relative to the pad, thebolsters optionally comprising one or more straps for securing the bodyposition between the laterally spaced bolsters, and comprising on a backsurface elements for engagement with the pivot platform; the pivotplatform comprising on an upper surface a plurality of arcuate trackscomprising engagement elements that are engageable with the engagementelements on the back of the support platform, and comprising on a backsurface adjustable and releasable surgical table engagement elements;wherein the pivoting support enables positional adjustment of a portionof the body resting thereon by rotational movement of the supportplatform along the path of the actuate tracks of the pivot platform todisplace the supported body position in the direction of rotationwherein the relative motion of the platforms is arcuate around a radiusof curvature between 10 and 100 inches, including between 30 and 60inches, and including a radius of about 42 inches; and wherein thecenterline of the arc is substantially parallel to the patient's spineand the longitudinal dimension of the table, and wherein the pivotplatform is rotated either left or right off the centerline wherein theextent of displacement from neutral position in each direction isbetween 10 degrees and 60 degrees, including between 20 and 40 degrees,and including 30 degrees.
 18. An apparatus for positioning a patientduring surgery according to claim 17, wherein the pivoting supportfurther comprises one or more of a pivoting actuator for moving thesupport platform relative to the pivot platform, the actuator selectedfrom a crank and a pusher/puller; a displacement guide for selecting theextent of displacement of the support platform from center along thearc; and a locking element for releasably locking the position of thedisplaced support platform.
 19. An apparatus for positioning a patientduring surgery according to claim 17: wherein the relative motion of theplatforms is arcuate around a radius of curvature that is adjustablyselectable and defined by a circle centered on the feet of the patientextending to the top of the pelvis/iliac crest.
 20. An apparatus forpositioning a patient during surgery according to claim 17, wherein thepivot platform is selected from an array of platforms each havingplurality of arcuate tracks that correspond with a radius of curvaturefor a particular patient population, the array including at least oneunique radius of curvature or ranges of radii of curvature, such as forexample, small size having a radius range from 20 to 30 inches, mediumsize having a radius range from 30 to 40 inches, and large size having aradius range from 40 to 60 inches.